Immunology
Survival requires immunity
• Full of potential pathogens, 10 commensals per human cell
• Encounter millions of pathogens daily
• Little pathology despite constant exposure
• Immune system constantly dealing with infection and damage
• Immune failure > guaranteed illness (AIDS, chemotherapy, allergies)
• Death > immediate decomposition (tissue acts as rich growth medium for bacteria)
What is immunity?
• Capacity to recognise material as foreign or non-functioning and to neutralise, eliminate
and metabolise them with/ without injury
• Able to differentiate between self and non-self
• Mechanisms allowing recognition of foreign or non-functional structures:
o Innate immunity
o Adaptive immunity
Two arms of the immune system, interactive and inter-dependent
Innate immunity Adaptive immunity
No time lag Lag period
Not antigen specific Antigen specific
No memory Development of memory
Definitions
• Immunology – the study of the immune system or immunity; the study of all aspects of
host defence against infection and or adverse consequences of immune responses
• Immune system – a versatile defence system that has evolved to protect animals from
invading pathogenic microorganisms and cancer
o able to generate a variety of cells and molecules capable of specifically
recognising and eliminating a variety of foreign invaders
o innate: large number of cells
o adaptive: small number of cells but trigger large response
Vaccination – immunological medical intervention
• smallpox vaccine led to eradication of the disease
• ability to control diseases using vaccines
o reduce strain on public health infrastructure
o e.g. polio
o e.g. control of SARS-CoV-2 has been achieved through vaccination
, How is an immune response organised?
• Entry of microbe – has a certain threshold, small entry will not create large response
• Pathogen multiplies > immune system fights back > pathogen levels decrease until
cleared
How does a vaccine work?
• Infections and vaccines induce immunological memory
• Adaptive immune system multiplies, targets specific cells and increases immune
response
• Immune system responds better when you have a prepped immune response
o Faster response during true infection
Learning objectives
- Know examples of why the immune system is important
- What was the first vaccine
- Give examples of diseases effectively controlled by vaccines
- Draw a graph outlining how an immune response develops against a challenge over time
, What can initiate an immune cell response?
1. Secreted molecules from self-cells or pathogens (cytokines)
2. Surface molecules on or shed from self-cells/ pathogens (CD markers)
3. Processed self or foreign antigens (Ag) displaced on self-cells
4. Any biomolecules can act as an antigen; protein, lipid, polysaccharide, combination
• Epitope is recognised by immune system > potential to elicit an immune response
How do external signals affect cells?
• Surface/ internal receptor (lock) > fits cognate ligand (key) > signal transduction >
appropriate cell response
o Antigen, cytokine, antibody > receptor > gene expression
o Cell responses: activation, cytokine secretion, protein synthesis, differentiation,
proliferation, migration, apoptosis
Learning objectives
- What can be an antigen?
- What is an epitope?
- What is a typical cell response following an external signal being recognised by a cell?
- Give examples of molecules that can induce an immune cell response.
- Give examples of immune cell responses.
Innate immunity
• Non-specific – anything seen as foreign/ non-functional is a potential target
• Physical barriers – first line of defence
o Skin, GIT, respiratory tract, nasopharynx, cilia, eyelashes, body hairs
• Physical defence mechanisms – secretion, mucous, bile, gastric acid, saliva
Skin
• Epidermis, dermis, hypodermis
• Cell type of epidermis: keratinocytes
o Filled with protein keratin
Survival requires immunity
• Full of potential pathogens, 10 commensals per human cell
• Encounter millions of pathogens daily
• Little pathology despite constant exposure
• Immune system constantly dealing with infection and damage
• Immune failure > guaranteed illness (AIDS, chemotherapy, allergies)
• Death > immediate decomposition (tissue acts as rich growth medium for bacteria)
What is immunity?
• Capacity to recognise material as foreign or non-functioning and to neutralise, eliminate
and metabolise them with/ without injury
• Able to differentiate between self and non-self
• Mechanisms allowing recognition of foreign or non-functional structures:
o Innate immunity
o Adaptive immunity
Two arms of the immune system, interactive and inter-dependent
Innate immunity Adaptive immunity
No time lag Lag period
Not antigen specific Antigen specific
No memory Development of memory
Definitions
• Immunology – the study of the immune system or immunity; the study of all aspects of
host defence against infection and or adverse consequences of immune responses
• Immune system – a versatile defence system that has evolved to protect animals from
invading pathogenic microorganisms and cancer
o able to generate a variety of cells and molecules capable of specifically
recognising and eliminating a variety of foreign invaders
o innate: large number of cells
o adaptive: small number of cells but trigger large response
Vaccination – immunological medical intervention
• smallpox vaccine led to eradication of the disease
• ability to control diseases using vaccines
o reduce strain on public health infrastructure
o e.g. polio
o e.g. control of SARS-CoV-2 has been achieved through vaccination
, How is an immune response organised?
• Entry of microbe – has a certain threshold, small entry will not create large response
• Pathogen multiplies > immune system fights back > pathogen levels decrease until
cleared
How does a vaccine work?
• Infections and vaccines induce immunological memory
• Adaptive immune system multiplies, targets specific cells and increases immune
response
• Immune system responds better when you have a prepped immune response
o Faster response during true infection
Learning objectives
- Know examples of why the immune system is important
- What was the first vaccine
- Give examples of diseases effectively controlled by vaccines
- Draw a graph outlining how an immune response develops against a challenge over time
, What can initiate an immune cell response?
1. Secreted molecules from self-cells or pathogens (cytokines)
2. Surface molecules on or shed from self-cells/ pathogens (CD markers)
3. Processed self or foreign antigens (Ag) displaced on self-cells
4. Any biomolecules can act as an antigen; protein, lipid, polysaccharide, combination
• Epitope is recognised by immune system > potential to elicit an immune response
How do external signals affect cells?
• Surface/ internal receptor (lock) > fits cognate ligand (key) > signal transduction >
appropriate cell response
o Antigen, cytokine, antibody > receptor > gene expression
o Cell responses: activation, cytokine secretion, protein synthesis, differentiation,
proliferation, migration, apoptosis
Learning objectives
- What can be an antigen?
- What is an epitope?
- What is a typical cell response following an external signal being recognised by a cell?
- Give examples of molecules that can induce an immune cell response.
- Give examples of immune cell responses.
Innate immunity
• Non-specific – anything seen as foreign/ non-functional is a potential target
• Physical barriers – first line of defence
o Skin, GIT, respiratory tract, nasopharynx, cilia, eyelashes, body hairs
• Physical defence mechanisms – secretion, mucous, bile, gastric acid, saliva
Skin
• Epidermis, dermis, hypodermis
• Cell type of epidermis: keratinocytes
o Filled with protein keratin
