(HAEMATOLOGY - CANCER)
2019/2020
MSc Biomedical Science
(Medical Molecular Biology)
, 1. Immunology introduction
Immunology
- Branch of biomedicine
- Studies structure and function of the immune system (IS)
- Areas of study:
- Defence of the body against microorganism and parasite attacks
- Discrimination between self and non-self
- How IS deals with foreign molecules
- How IS recognises and deals with neoplastic and virally transformed cells
- Transplanted organs, cells and proteins
- What happens when IS attacks itself
Discrimination between self and non-self
Self (host cells) Non-self (foreign cells)
Immune response
- When an organism is threatened by viruses, microorganisms or cancer cells
- Provides protection
Tolerance
- Lack of immune response
- IS does not mount a response against self (host cells)
Autoimmunity
- IS mounts a response against self
- If IS responds against self => tolerance to self is lost => autoimmune diseases
- Autoimmune diseases in humans (examples):
- Asthma, Lupus, Arthritis
Immune system basics
ANTIGEN:
- Protein molecules recognised by the IS
Antigen as foreign
- Anything that causes an immune response - IS specifically reacts against them
- Can be:
- HARMLESS (grass pollen,…) ANTIBODIES:
- Antigen-specific proteins
- HARMFUL (flu virus, bacteria,…) - Produced by B lymphocytes (B cells)
- Disease causing antigen => PATHOGEN - Produced in response to antigen
- IS is designed to protect the body from pathogens exposure
Development of IS in humans
- Development begins in embryo
- IS starts with hematopoietic stem cells (‘blood making’ cells) ERYTHROCYTES:
- Stem cells differentiate into: - Red blood cells
- GRANULOCYTES MEGAKARYOCYTES:
- MONOCYTES major players in the IS - Blood clotting
- LYMPHOCYTES
- ERYTHROCYTES cells in the blood
- MEGAKARYOCYTES not involved in immune function
- Production and differentiation of stem cells continues throughout the lifetime
- By the time a baby is born, IS is a collection of tissues
(blood, lymphatic system, thymus, spleen, skin, mucosa)
Thymus
T lymphocyte (T cell)
Lymphoid stem cell NK lymphocyte (natural killer cell)
B lymphocyte
Puripotent stem
cell
Erythrocyte
Myeloid stem
cell Megakaryocyte (blood clotting)
Macrophage
Monocyte
Granulocyte
, 2. Innate and adaptive immunity
Pathogen infection
- Is consists of a big range of mechanisms and cells
- Huge range of pathogens (worms, protozoa, fungi, bacteria, viruses)
- Big size range of pathogens
Different types of cells needed to fight different pathogens
- Major natural ways of contracting pathogens:
- Respiratory system
- Digestive system made up of mucosal surfaces => less protected => prone to infection
- Sexual transmission
ROUTES OF INFECTION FOR PATHOGENS (examples)
ROUTE OF MODE OF PATHOGEN DISEASE TYPE OF
ENTRY TRANSMISSION PATHOGEN
Mucosal surfaces
Inhalation or ingestion Influenza virus Influenza Orthomyxovirus
Mouth and of infected material Streptococcus Tonsillitis Gram-positive
respiratory tract pyogenes bacterium
Most vulnerable
Spores Bacillus anthracis Inhalation anthrax Gram-positive
bacterium
Gastrointestinal Contaminated Hepatitis A Jaundice Picornavirus
tract water/food
Sexual transmission Human Acquired Retrovirus
Reproductive (infected blood) immunodeficiency immunodeficiency
tract + other virus (HIV) syndrome (AIDS)
routes Sexual transmission Neisseria Gonorrhoea Gram-negative
gonorrhoeae bacterium
Opportunistic pathogens
immunocom
Not harmful
Resident microbiota Candida Thrush Fungus
promised
abicans
unless
Resident lung Pneumocystis Pneumonia Fungus
microbiota jirovecii
External epithelia
External surface Physical contact Trichophyton Athlete’s foot Fungus
Can be easily
contracted
Wounds and Puncture wounds Clostridium tetani Tetanus Gram-positive
abrasions bacterium
Mosquito bites Plasmodium spp. Malaria Protozoan
Insect bites (anopheles)
Dear tick bites Borella Lyme disease Bacterium
burgdorferi (spirochete)
Infection defence mechanisms
1. Mechanical/chemical barriers
2. Innate immunity
3. Adaptive + innate immunity cooperation