BBS2001 THREADS AND
DEFENCE MECHANISMS
Cases and practicals
S HERMANS
FHML
Maastricht university
,CONTENTS
Case 1 The first aid troops ....................................................................................................................................................... 6
Blood cells............................................................................................................................................................................... 6
Hemostasis ............................................................................................................................................................................. 6
How is bleeding stopped? ............................................................................................................................................... 7
How is coagulation stopped? ......................................................................................................................................... 9
Sterile inflammation ........................................................................................................................................................ 9
Consolidation assignment 1 ...................................................................................................................................................11
1) The differenc es and similarities between venous and arterial thrombosis ...................................................11
2) the targets for treatment of arterial and venous thrombosis ..........................................................................11
therapeutic agents, and scheme ......................................................................................................................................11
Practical leukocyte / hemosurf .............................................................................................................................................12
Case 2 swollen fingers ............................................................................................................................................................14
general structure of a bacteria .........................................................................................................................................14
Gram positive VS gram negative ......................................................................................................................................14
Gram staining:......................................................................................................................................................................15
classification of bacteria ....................................................................................................................................................15
bacterial replication: binary fission (asexual → one mother two daugther cells) ..................................................16
Growth of the bacteria.......................................................................................................................................................17
How does the innate immune system work? .................................................................................................................17
Recognition of intruders................................................................................................................................................17
terminal complement proteins lyse phatogens by forming membrane pores: ..................................................20
the smaller fragments C3a and C5a are anaphylatoxins .........................................................................................21
antibacterial peptides kill pathogens by perturbing their membranes: ...............................................................21
The classical pathway: ...................................................................................................................................................22
lectin pathway:................................................................................................................................................................22
Trigger of the innate immune response .....................................................................................................................22
The first line of defence: macrophages ......................................................................................................................22
Inflammasomes: recognition bacteria ........................................................................................................................24
Neutrophils are the first immune cells to be reqruited...........................................................................................24
natural killer cells: defense agains intracellular pathogens ....................................................................................25
clearing of bacteria: .......................................................................................................................................................25
the differenc e between inflammation and infection ...................................................................................................25
pus..........................................................................................................................................................................................25
Consolidation assignment threat and defense 2: bacterial infections .........................................................................26
macroscopic and microsopic bacterial classification:...................................................................................................26
1
, The structure & function of the innate immune system of the GI tract. compare how these cells respond to
an infection with how cells respond during a skin infection .......................................................................................26
Differences with skin infections:..................................................................................................................................27
structure of the innate GI immune system................................................................................................................27
immunological detection methods ..................................................................................................................................28
Elisa: enzyme linked immunosorbent assay..............................................................................................................28
Sandwich ELISA ...............................................................................................................................................................28
Flow cytometry ...............................................................................................................................................................29
Immunohistochemistry .................................................................................................................................................30
FLuorescent and confocal microscope .......................................................................................................................30
Western blotting.............................................................................................................................................................31
Which technique is most suitable for detecting a specific bacterial strain? .......................................................33
Lectur e Workshop immunological detection techniques. ...............................................................................................34
Case 3 coping with intruders from different origin ...........................................................................................................36
Classification of particulate matter : according to size .................................................................................................36
Toxic effects of the PM to pulmonary exposure and the defence ............................................................................36
Mechanical.......................................................................................................................................................................36
Toxic effect of the air pollution: Overproduction of ROS and RNS with result oxidative stress ...........................37
Immune defence of the lungs: ..........................................................................................................................................37
ROS, Reactive Oxygen Species ..........................................................................................................................................37
Antioxidant network of the lungs: ...................................................................................................................................38
Drug metabolism, and CYP450 (cytochrome P 450) .....................................................................................................39
EXAMple questions .............................................................................................................................................................39
consolidation assignemnt 3 ...................................................................................................................................................40
toxic nanoparticles in our diet ..........................................................................................................................................40
Different routes of exposure of the gut to nanoparticles............................................................................................40
overarching damaging effects of these toxins to the GUT ..........................................................................................40
How can the gut cope with this toxicity & to what ex tend? .......................................................................................41
The GI tract’s antioxidant activity................................................................................................................................42
guarantee of the safe applications...................................................................................................................................42
Case 4 influenza .......................................................................................................................................................................43
What is a viras and the Structure of a virus ...................................................................................................................43
Viral replication ...................................................................................................................................................................43
Exposure to a virus:.............................................................................................................................................................45
Host and tissue tropism: ....................................................................................................................................................45
The influenza virus:.............................................................................................................................................................46
Antiviral agents against influenza ....................................................................................................................................46
2
, Reproduction of infl uenza .................................................................................................................................................47
How does the innate immune system fight a virus?.....................................................................................................47
How does the adaptive immune system r ecognise and fight a virus? ......................................................................50
Antigen processing and presentation .........................................................................................................................51
T -effector cells................................................................................................................................................................53
Immune system in the lungs .............................................................................................................................................57
Difference between the recognition of a virus for the adaptive and innate immune system ..............................57
Consolidation assignment 4 ...................................................................................................................................................57
differnece Influenza A, B and C: .......................................................................................................................................57
Influenza classification .......................................................................................................................................................58
Antigenic drift, shift, pandemy and epidemy and seasonal and pandemic influenza ............................................58
Influenza A H1N1: swine flu/ Mexican flu and avian H5N1 influenza .......................................................................59
Specific receptors in pigs make them suitable intermediate hosts in the development of new influenza
strains:...................................................................................................................................................................................59
Avian viruses are thought to have the potential to cause an pandemic...................................................................60
Describe how viral antigens are taken up in the Peyers patches and how they are presented to T cells:
transcytosis ..........................................................................................................................................................................60
Describe the route and migration/extravasation of the helper T cell from the axillary lymph node (arm pit
lymph nodes) to the Peyers patch in detail....................................................................................................................60
Practical lymphoid organs: preparation ..............................................................................................................................61
Virtual microscopy summary workfile .................................................................................................................................64
TONSILS (folded lining of lymphoid tissue).....................................................................................................................65
APPENDIX (GALT), lymphoid areas: purple, part of mucosa directly under folded epithelium............................66
Peyer’s patches:...................................................................................................................................................................67
Lymph nodes; General histology ......................................................................................................................................67
Lymph nodes; Immunohistology ......................................................................................................................................68
Lymph nodes; Immunohistology ‘Macrophage staining’ ............................................................................................69
Lymph nodes; Immunohistology ‘B-cell (IgM) staining’ ...............................................................................................69
Lymph nodes; Immunohistology ‘T-cell (TCR) staining’ ...............................................................................................69
Lymph nodes; Immunohistology ‘T-helper cell (CD4) staining’ + ‘T-cytotoxic cell (CD8) staining’.......................69
Lymph nodes; Immunohistology ‘HEV (endotheliu m) staining’..................................................................................70
Lymph nodes; Immunohistology ‘Dendritic cell (MHC-class II) staining’ ..................................................................70
Lymph nodes; Immunohistology ‘Plasma cell (intracellular Ig) staining’ ..................................................................70
Spleen; General histology ..................................................................................................................................................71
Spleen; Immunohistology ‘Reticulum staining’ .............................................................................................................72
Spleen; Immunohistology ‘Macrophage staining’ ........................................................................................................72
Spleen; Immunohistology ‘B-cell (IgM) staining’ ...........................................................................................................73
3
, Spleen; Immunohistology ‘Endothelium staining’.........................................................................................................73
Spleen; Immunohistology ‘T-cell (TCR) staining’ ...........................................................................................................73
Spleen; Immunohistology ‘T-helper cell (CD4)+ CD8 cytotoxic staining’ ..................................................................74
Spleen; Immunohistology ‘Dendritic cell (MHC-class II) staining’ ..............................................................................74
Case 5 Pathogenic or commensal.........................................................................................................................................75
Commensal vs pathogenic bacteria .................................................................................................................................75
How do pathogens escape the immune system............................................................................................................75
Virulence factors: ................................................................................................................................................................75
Pathogenicity islands:.........................................................................................................................................................76
Virulence factors of pathogenic E. coli ............................................................................................................................77
How are virulence factors transferred between bacteria: ..........................................................................................77
How are B cells activated by bacterial infections?........................................................................................................78
CD4 T cells, folicular dendritic cells and B cells,.............................................................................................................79
Levels of antibodies during the primary and secondary infections ...........................................................................86
CD4 Th1 Cells. ......................................................................................................................................................................87
Consolidation assignment 5 ...................................................................................................................................................87
Helminths..............................................................................................................................................................................87
Immune r esponse against helmints.................................................................................................................................89
Summary practical lack of T helper cells .............................................................................................................................91
Case 6 vaccination and antibiotics .......................................................................................................................................94
Why is seasonal flu vaccine given every year? ..............................................................................................................94
Which target of neutralizing antibodies is not sensitive to antigenic variation and why is this important in the
development of universal vaccines?................................................................................................................................94
The goal of vaccination .....................................................................................................................................................94
Which types of vaccines exist? .........................................................................................................................................94
Antibiotics.............................................................................................................................................................................95
β -lactams .............................................................................................................................................................................95
Classification of β-lactams .................................................................................................................................................95
Cephalosporins have 4 generations:................................................................................................................................95
Other types of antibiotics:.................................................................................................................................................96
Resistance to β-lactams .....................................................................................................................................................96
β-lactamases: .......................................................................................................................................................................97
Different ESBL types, their prevalence and origin.........................................................................................................97
General antibiotic resistance ............................................................................................................................................97
Lab analysis...........................................................................................................................................................................98
Consolidation assignment 6 ...................................................................................................................................................98
Why does antimicrobial resistance occur? .....................................................................................................................98
4
, Impact of travel and migration on the acquisition and spread of resistance genes ...............................................99
How can antimicrobial resistance genes can be transferred ? ...................................................................................99
Lab practical microbiology .................................................................................................................................................. 100
Skin bacteria...................................................................................................................................................................... 100
2.Flora of the skin and nose ........................................................................................................................................... 101
3. flora of the intestinal trackt: ...................................................................................................................................... 101
Determine the samples X, Y and Z ................................................................................................................................ 101
Cytokine tables...................................................................................................................................................................... 102
Antibodies function and which cytokine helps them switch.................................................................................... 103
5
,CASE 1 THE FIRST AID TROOPS
BLO O D CELLS
Non-specific white blood cells: innate immune system
• Neutrophils: phagocytosis and killing of microorganisms
neutrophils act as the first responders to infections / pathogens. They phagocytose (eat) invading
organisms and release cytotoxins (cell killing substances). They respond to infections inside the body
and in the skin. Chemotaxis is the process that directs them to the skin. Pus is dead neutrophils,
bacteria and skin cells. A high neutrophil count is caused by an infection.
• Basophils: control responses to parasites
primary responsible for allergic reactions. They contain histamine and release chemicals that cause
inflammation. They are found in and outside vessels.
• Eosinophils: killing of antibody coated parasites through the release of their granule content
(cytokines).
They are found in and outside vessels , in the GI track for example where they are involved in food
allergies. It is an “acid loving cell”.
• NK cells: natural killer cells they can kill human cells that are infected with a virus.
• Monocytes: differentiate into macrophages and facilitate health and repair. They are the circulating
precursor of macrophages, when they leave the blood stream, they are macrophages.
Specific immune response white blood cells: adaptive immune system
• Lymphocytes: they have receptor molecules on their surface and with these receptors they bind to
antigens on foreign molecules. Each lymphocyte has a specific antigen. Once stimulated by binding of
an antigen, they multiply into identical cells. B lymphocytes (humoral response (antibody production)
and T lymphocytes: cellular response (cytotoxic or T helper cells).
Other blood cells:
• Platelets/ thrombocytes: Fragments of cytoplasm of a megakaryocyte. they are colorless and have no
nucleus, granules filled with cytokines and growth factors. Their lifespan is about 10 days. They lay a
role in preventing blood loss, but they also act as immune cells and mediate the inflammatory
response.
• Erythrocytes / red blood cells: deliver O 2 to the tissues, no nucleus, hemoglobin rich cytoplasm. They
also play a role in the immune response: when lysed by a bacteria, hemoglobin is released.
Hemoglobin releases free radicals which can kill the pathogen.
Inflammation: a localized protective response caused by injury or destruction of tissue, which serves to destroy
pathogens.
HEMO STASI S
The process to keep blood inside a damaged blood vessel
W HAT I S BLEEDI NG? epidermis
bleeding is the loss of blood, when blood leaves through the skin, it is called
external bleeding. when a wound is bleeding, the basement membrane and dermis
the dermis underneath, and the endothelium of the blood vessel are
damaged. The blood vessels are located in the dermis of the skin. An Subcutaneous tissue
abrasion: only the epidermis is broken.
6
, HO W I S BLEEDI NG STO P PED?
1) Vasoconstriction to decrease the blood flow through the wounded vessel. Parac rine molecules are
released from the damaged blood vessel.
2) Temporary blockage of the break by a platelet plug. The damaged vessel wall exposes collagen and
other chemicals. On the platelets are molecules called integrins:
• Glycoprotein 1 b: binds to VWF, VWF binds to collagen
• Glycoprotein IIbIIIa: binds to fibrinogen (aiding in platelet aggregation)
The von Willebrand factor (VWF) bind to glycoprotein 1b on the platelet and to collagen. VWF thus
couples the platelet to the collagen of the blood vessel. Thi s results in the activation of the platelet
(via a conformational change/ change in shape), resulting in the platelets releasing their granule
contents:
• α-granules: contain fibrinogen and VWF
• dense granules: contain serotonin, ADP(role in platelet aggregation) and Ca 2+
These factors are stored by granules, so that they can be released very quickly when needed (so they
don’t need to be synthesized anymore when needed.)
PAF: platelet activating factor is also secreted and will result in the activation of even more platelets.
PAF converts platelet membrane phospholipids into thromboxane A2 and serotonin , which serve as
vasoconstrictors and contribute to pla telet aggregation.
Localization of platelets: platelets adhere only at the damaged spot. Intact vascular cells convert
their membrane lipids into prostacyclin and release NO, which both block platelet aggregation.
3) Coagulation :due to a series of linked enzymatic reactions, fibrin is formed which helps to stabilize the
platelet plug. The coagulation cascade is thus a series of enzymatic reactions that results in the
production of thrombin, that can conversion of fibrin into fibrinogen.
• The extrinsic pathway/ initiation: Tissue factor exposed at the site of damage activated factor
VII.
• The intrinsic pathway / propagation: uses proteins that are already present in the plasma. It
starts with exposed collagen in the damaged tissue, that will activate factor XII.
➔ One pathway activates the other
7
DEFENCE MECHANISMS
Cases and practicals
S HERMANS
FHML
Maastricht university
,CONTENTS
Case 1 The first aid troops ....................................................................................................................................................... 6
Blood cells............................................................................................................................................................................... 6
Hemostasis ............................................................................................................................................................................. 6
How is bleeding stopped? ............................................................................................................................................... 7
How is coagulation stopped? ......................................................................................................................................... 9
Sterile inflammation ........................................................................................................................................................ 9
Consolidation assignment 1 ...................................................................................................................................................11
1) The differenc es and similarities between venous and arterial thrombosis ...................................................11
2) the targets for treatment of arterial and venous thrombosis ..........................................................................11
therapeutic agents, and scheme ......................................................................................................................................11
Practical leukocyte / hemosurf .............................................................................................................................................12
Case 2 swollen fingers ............................................................................................................................................................14
general structure of a bacteria .........................................................................................................................................14
Gram positive VS gram negative ......................................................................................................................................14
Gram staining:......................................................................................................................................................................15
classification of bacteria ....................................................................................................................................................15
bacterial replication: binary fission (asexual → one mother two daugther cells) ..................................................16
Growth of the bacteria.......................................................................................................................................................17
How does the innate immune system work? .................................................................................................................17
Recognition of intruders................................................................................................................................................17
terminal complement proteins lyse phatogens by forming membrane pores: ..................................................20
the smaller fragments C3a and C5a are anaphylatoxins .........................................................................................21
antibacterial peptides kill pathogens by perturbing their membranes: ...............................................................21
The classical pathway: ...................................................................................................................................................22
lectin pathway:................................................................................................................................................................22
Trigger of the innate immune response .....................................................................................................................22
The first line of defence: macrophages ......................................................................................................................22
Inflammasomes: recognition bacteria ........................................................................................................................24
Neutrophils are the first immune cells to be reqruited...........................................................................................24
natural killer cells: defense agains intracellular pathogens ....................................................................................25
clearing of bacteria: .......................................................................................................................................................25
the differenc e between inflammation and infection ...................................................................................................25
pus..........................................................................................................................................................................................25
Consolidation assignment threat and defense 2: bacterial infections .........................................................................26
macroscopic and microsopic bacterial classification:...................................................................................................26
1
, The structure & function of the innate immune system of the GI tract. compare how these cells respond to
an infection with how cells respond during a skin infection .......................................................................................26
Differences with skin infections:..................................................................................................................................27
structure of the innate GI immune system................................................................................................................27
immunological detection methods ..................................................................................................................................28
Elisa: enzyme linked immunosorbent assay..............................................................................................................28
Sandwich ELISA ...............................................................................................................................................................28
Flow cytometry ...............................................................................................................................................................29
Immunohistochemistry .................................................................................................................................................30
FLuorescent and confocal microscope .......................................................................................................................30
Western blotting.............................................................................................................................................................31
Which technique is most suitable for detecting a specific bacterial strain? .......................................................33
Lectur e Workshop immunological detection techniques. ...............................................................................................34
Case 3 coping with intruders from different origin ...........................................................................................................36
Classification of particulate matter : according to size .................................................................................................36
Toxic effects of the PM to pulmonary exposure and the defence ............................................................................36
Mechanical.......................................................................................................................................................................36
Toxic effect of the air pollution: Overproduction of ROS and RNS with result oxidative stress ...........................37
Immune defence of the lungs: ..........................................................................................................................................37
ROS, Reactive Oxygen Species ..........................................................................................................................................37
Antioxidant network of the lungs: ...................................................................................................................................38
Drug metabolism, and CYP450 (cytochrome P 450) .....................................................................................................39
EXAMple questions .............................................................................................................................................................39
consolidation assignemnt 3 ...................................................................................................................................................40
toxic nanoparticles in our diet ..........................................................................................................................................40
Different routes of exposure of the gut to nanoparticles............................................................................................40
overarching damaging effects of these toxins to the GUT ..........................................................................................40
How can the gut cope with this toxicity & to what ex tend? .......................................................................................41
The GI tract’s antioxidant activity................................................................................................................................42
guarantee of the safe applications...................................................................................................................................42
Case 4 influenza .......................................................................................................................................................................43
What is a viras and the Structure of a virus ...................................................................................................................43
Viral replication ...................................................................................................................................................................43
Exposure to a virus:.............................................................................................................................................................45
Host and tissue tropism: ....................................................................................................................................................45
The influenza virus:.............................................................................................................................................................46
Antiviral agents against influenza ....................................................................................................................................46
2
, Reproduction of infl uenza .................................................................................................................................................47
How does the innate immune system fight a virus?.....................................................................................................47
How does the adaptive immune system r ecognise and fight a virus? ......................................................................50
Antigen processing and presentation .........................................................................................................................51
T -effector cells................................................................................................................................................................53
Immune system in the lungs .............................................................................................................................................57
Difference between the recognition of a virus for the adaptive and innate immune system ..............................57
Consolidation assignment 4 ...................................................................................................................................................57
differnece Influenza A, B and C: .......................................................................................................................................57
Influenza classification .......................................................................................................................................................58
Antigenic drift, shift, pandemy and epidemy and seasonal and pandemic influenza ............................................58
Influenza A H1N1: swine flu/ Mexican flu and avian H5N1 influenza .......................................................................59
Specific receptors in pigs make them suitable intermediate hosts in the development of new influenza
strains:...................................................................................................................................................................................59
Avian viruses are thought to have the potential to cause an pandemic...................................................................60
Describe how viral antigens are taken up in the Peyers patches and how they are presented to T cells:
transcytosis ..........................................................................................................................................................................60
Describe the route and migration/extravasation of the helper T cell from the axillary lymph node (arm pit
lymph nodes) to the Peyers patch in detail....................................................................................................................60
Practical lymphoid organs: preparation ..............................................................................................................................61
Virtual microscopy summary workfile .................................................................................................................................64
TONSILS (folded lining of lymphoid tissue).....................................................................................................................65
APPENDIX (GALT), lymphoid areas: purple, part of mucosa directly under folded epithelium............................66
Peyer’s patches:...................................................................................................................................................................67
Lymph nodes; General histology ......................................................................................................................................67
Lymph nodes; Immunohistology ......................................................................................................................................68
Lymph nodes; Immunohistology ‘Macrophage staining’ ............................................................................................69
Lymph nodes; Immunohistology ‘B-cell (IgM) staining’ ...............................................................................................69
Lymph nodes; Immunohistology ‘T-cell (TCR) staining’ ...............................................................................................69
Lymph nodes; Immunohistology ‘T-helper cell (CD4) staining’ + ‘T-cytotoxic cell (CD8) staining’.......................69
Lymph nodes; Immunohistology ‘HEV (endotheliu m) staining’..................................................................................70
Lymph nodes; Immunohistology ‘Dendritic cell (MHC-class II) staining’ ..................................................................70
Lymph nodes; Immunohistology ‘Plasma cell (intracellular Ig) staining’ ..................................................................70
Spleen; General histology ..................................................................................................................................................71
Spleen; Immunohistology ‘Reticulum staining’ .............................................................................................................72
Spleen; Immunohistology ‘Macrophage staining’ ........................................................................................................72
Spleen; Immunohistology ‘B-cell (IgM) staining’ ...........................................................................................................73
3
, Spleen; Immunohistology ‘Endothelium staining’.........................................................................................................73
Spleen; Immunohistology ‘T-cell (TCR) staining’ ...........................................................................................................73
Spleen; Immunohistology ‘T-helper cell (CD4)+ CD8 cytotoxic staining’ ..................................................................74
Spleen; Immunohistology ‘Dendritic cell (MHC-class II) staining’ ..............................................................................74
Case 5 Pathogenic or commensal.........................................................................................................................................75
Commensal vs pathogenic bacteria .................................................................................................................................75
How do pathogens escape the immune system............................................................................................................75
Virulence factors: ................................................................................................................................................................75
Pathogenicity islands:.........................................................................................................................................................76
Virulence factors of pathogenic E. coli ............................................................................................................................77
How are virulence factors transferred between bacteria: ..........................................................................................77
How are B cells activated by bacterial infections?........................................................................................................78
CD4 T cells, folicular dendritic cells and B cells,.............................................................................................................79
Levels of antibodies during the primary and secondary infections ...........................................................................86
CD4 Th1 Cells. ......................................................................................................................................................................87
Consolidation assignment 5 ...................................................................................................................................................87
Helminths..............................................................................................................................................................................87
Immune r esponse against helmints.................................................................................................................................89
Summary practical lack of T helper cells .............................................................................................................................91
Case 6 vaccination and antibiotics .......................................................................................................................................94
Why is seasonal flu vaccine given every year? ..............................................................................................................94
Which target of neutralizing antibodies is not sensitive to antigenic variation and why is this important in the
development of universal vaccines?................................................................................................................................94
The goal of vaccination .....................................................................................................................................................94
Which types of vaccines exist? .........................................................................................................................................94
Antibiotics.............................................................................................................................................................................95
β -lactams .............................................................................................................................................................................95
Classification of β-lactams .................................................................................................................................................95
Cephalosporins have 4 generations:................................................................................................................................95
Other types of antibiotics:.................................................................................................................................................96
Resistance to β-lactams .....................................................................................................................................................96
β-lactamases: .......................................................................................................................................................................97
Different ESBL types, their prevalence and origin.........................................................................................................97
General antibiotic resistance ............................................................................................................................................97
Lab analysis...........................................................................................................................................................................98
Consolidation assignment 6 ...................................................................................................................................................98
Why does antimicrobial resistance occur? .....................................................................................................................98
4
, Impact of travel and migration on the acquisition and spread of resistance genes ...............................................99
How can antimicrobial resistance genes can be transferred ? ...................................................................................99
Lab practical microbiology .................................................................................................................................................. 100
Skin bacteria...................................................................................................................................................................... 100
2.Flora of the skin and nose ........................................................................................................................................... 101
3. flora of the intestinal trackt: ...................................................................................................................................... 101
Determine the samples X, Y and Z ................................................................................................................................ 101
Cytokine tables...................................................................................................................................................................... 102
Antibodies function and which cytokine helps them switch.................................................................................... 103
5
,CASE 1 THE FIRST AID TROOPS
BLO O D CELLS
Non-specific white blood cells: innate immune system
• Neutrophils: phagocytosis and killing of microorganisms
neutrophils act as the first responders to infections / pathogens. They phagocytose (eat) invading
organisms and release cytotoxins (cell killing substances). They respond to infections inside the body
and in the skin. Chemotaxis is the process that directs them to the skin. Pus is dead neutrophils,
bacteria and skin cells. A high neutrophil count is caused by an infection.
• Basophils: control responses to parasites
primary responsible for allergic reactions. They contain histamine and release chemicals that cause
inflammation. They are found in and outside vessels.
• Eosinophils: killing of antibody coated parasites through the release of their granule content
(cytokines).
They are found in and outside vessels , in the GI track for example where they are involved in food
allergies. It is an “acid loving cell”.
• NK cells: natural killer cells they can kill human cells that are infected with a virus.
• Monocytes: differentiate into macrophages and facilitate health and repair. They are the circulating
precursor of macrophages, when they leave the blood stream, they are macrophages.
Specific immune response white blood cells: adaptive immune system
• Lymphocytes: they have receptor molecules on their surface and with these receptors they bind to
antigens on foreign molecules. Each lymphocyte has a specific antigen. Once stimulated by binding of
an antigen, they multiply into identical cells. B lymphocytes (humoral response (antibody production)
and T lymphocytes: cellular response (cytotoxic or T helper cells).
Other blood cells:
• Platelets/ thrombocytes: Fragments of cytoplasm of a megakaryocyte. they are colorless and have no
nucleus, granules filled with cytokines and growth factors. Their lifespan is about 10 days. They lay a
role in preventing blood loss, but they also act as immune cells and mediate the inflammatory
response.
• Erythrocytes / red blood cells: deliver O 2 to the tissues, no nucleus, hemoglobin rich cytoplasm. They
also play a role in the immune response: when lysed by a bacteria, hemoglobin is released.
Hemoglobin releases free radicals which can kill the pathogen.
Inflammation: a localized protective response caused by injury or destruction of tissue, which serves to destroy
pathogens.
HEMO STASI S
The process to keep blood inside a damaged blood vessel
W HAT I S BLEEDI NG? epidermis
bleeding is the loss of blood, when blood leaves through the skin, it is called
external bleeding. when a wound is bleeding, the basement membrane and dermis
the dermis underneath, and the endothelium of the blood vessel are
damaged. The blood vessels are located in the dermis of the skin. An Subcutaneous tissue
abrasion: only the epidermis is broken.
6
, HO W I S BLEEDI NG STO P PED?
1) Vasoconstriction to decrease the blood flow through the wounded vessel. Parac rine molecules are
released from the damaged blood vessel.
2) Temporary blockage of the break by a platelet plug. The damaged vessel wall exposes collagen and
other chemicals. On the platelets are molecules called integrins:
• Glycoprotein 1 b: binds to VWF, VWF binds to collagen
• Glycoprotein IIbIIIa: binds to fibrinogen (aiding in platelet aggregation)
The von Willebrand factor (VWF) bind to glycoprotein 1b on the platelet and to collagen. VWF thus
couples the platelet to the collagen of the blood vessel. Thi s results in the activation of the platelet
(via a conformational change/ change in shape), resulting in the platelets releasing their granule
contents:
• α-granules: contain fibrinogen and VWF
• dense granules: contain serotonin, ADP(role in platelet aggregation) and Ca 2+
These factors are stored by granules, so that they can be released very quickly when needed (so they
don’t need to be synthesized anymore when needed.)
PAF: platelet activating factor is also secreted and will result in the activation of even more platelets.
PAF converts platelet membrane phospholipids into thromboxane A2 and serotonin , which serve as
vasoconstrictors and contribute to pla telet aggregation.
Localization of platelets: platelets adhere only at the damaged spot. Intact vascular cells convert
their membrane lipids into prostacyclin and release NO, which both block platelet aggregation.
3) Coagulation :due to a series of linked enzymatic reactions, fibrin is formed which helps to stabilize the
platelet plug. The coagulation cascade is thus a series of enzymatic reactions that results in the
production of thrombin, that can conversion of fibrin into fibrinogen.
• The extrinsic pathway/ initiation: Tissue factor exposed at the site of damage activated factor
VII.
• The intrinsic pathway / propagation: uses proteins that are already present in the plasma. It
starts with exposed collagen in the damaged tissue, that will activate factor XII.
➔ One pathway activates the other
7
