CBI-30306
HUMAN AND
VETERINARY
IMMUNOLOGY
SUMMARY
1
, CBI-30306 HUMAN AND VETERINARY
IMMUNOLOGY
I. INTRODUCTION TO THE IMMUNE SYSTEM
I.I MAIN FUNCTIONS OF TH E IMMUNE SYSTEM
- Protection against infectious microbes (non-self)
o Intracellular (viruses, some bacteria and parasites)
o Extracellular (most bacteria and parasites, fungi)
The immune system handles intracellular and extracellular microbes differently.
- Protection against modified self
o Cancer/tumour cells or transformed cells
In abnormal situations, the immune system can mistake self for non-self and launch an attack against the body’s own cells or
tissues autoimmune disease. It can also occur that the immune system responds to a seemingly harmless foreign
substance (antigen is then allergen) allergy
I.II INNATE VERSUS ACQUIR ED (ADAPTIVE) IMMUNI TY
Pathogen recognition
- Innate response is the same after repeated exposure to the same pathogen (fast (works within hours), can’t proliferate, less
specific since it recognize PAMPs)
- Adaptive response matures over time; repeated exposure leads to faster response this is why we vaccinate people.
When someone is vaccinated against a virus f.e., you can respond more quickly to eliminate the virus when you’re really
infected with it. (slow (works within days), can proliferate, more specific since it recognizes one amino acid from the
antigen)
Pathogen removal
- Early response : innate immunity removes most of microbes
- Later response : lymphocyte generate adaptive immune response and specific memory
Most organisms only have innate immunity (only vertebrates have adaptive immunity)
Leukocytes are all types of white blood cells. Since 10% of all your white blood cells are monocytes and 72% of your white
blood cells are granulocytes, at least 80% of your white blood cells accounts for innate immunity.
There’s a lot of interaction between the different cell
types of the immune system.
Several cytokines / growth factors lead to
differentiation of stem cells into different leukocytes.
Pluripotent stem cells in the fetal liver and bone
marrow, known as hematopoietic stem cells (HSCs),
give rise to all lineages of blood cells, including
lymphocytes. The common myeloid progenitor
develops mostly cells for innate immunity, while the
common lymphoid progenitor is more important for
adaptive immunity.
Many nuclear events in lymphocyte development are
regulated by epigenetic mechanisms.
Figure 1 - Innate and adaptive immunity (also natural antibodies are
part of innate immunity)
You can live without adaptive immunity, but not without innate immunity. We can illustrate this by looking at a bacterial infection.
A bacterium divides approximately every 20 minutes in your body. It takes way too long for the adaptive immune system to get
activated and therefore innate immunity is really crucial. Namely, innate immunity is fast and kills by far most microbes (99.9%).
You have both active and passive immunity. Active immunity is conferred by a host response to a microbe or microbial antigen,
whereas passive immunity is conferred by adoptive transfer of antibodies or T lymphocytes specific for the microbe (also occurs
during pregnancy from mother to foetus). Both forms of immunity provide resistance to infection and are specific for microbial
antigens, but only active immune responses generate immunologic memory.
The survival and pathogenicity of microbes in a host are critically influenced by the ability of the microbes to evade or resist the
effector mechanisms of immunity.
Many microbes establish latent, or persistent, infections in which the immune response controls but does not eliminate the
microbe and the microbe survives without propagating the infection.
2
HUMAN AND
VETERINARY
IMMUNOLOGY
SUMMARY
1
, CBI-30306 HUMAN AND VETERINARY
IMMUNOLOGY
I. INTRODUCTION TO THE IMMUNE SYSTEM
I.I MAIN FUNCTIONS OF TH E IMMUNE SYSTEM
- Protection against infectious microbes (non-self)
o Intracellular (viruses, some bacteria and parasites)
o Extracellular (most bacteria and parasites, fungi)
The immune system handles intracellular and extracellular microbes differently.
- Protection against modified self
o Cancer/tumour cells or transformed cells
In abnormal situations, the immune system can mistake self for non-self and launch an attack against the body’s own cells or
tissues autoimmune disease. It can also occur that the immune system responds to a seemingly harmless foreign
substance (antigen is then allergen) allergy
I.II INNATE VERSUS ACQUIR ED (ADAPTIVE) IMMUNI TY
Pathogen recognition
- Innate response is the same after repeated exposure to the same pathogen (fast (works within hours), can’t proliferate, less
specific since it recognize PAMPs)
- Adaptive response matures over time; repeated exposure leads to faster response this is why we vaccinate people.
When someone is vaccinated against a virus f.e., you can respond more quickly to eliminate the virus when you’re really
infected with it. (slow (works within days), can proliferate, more specific since it recognizes one amino acid from the
antigen)
Pathogen removal
- Early response : innate immunity removes most of microbes
- Later response : lymphocyte generate adaptive immune response and specific memory
Most organisms only have innate immunity (only vertebrates have adaptive immunity)
Leukocytes are all types of white blood cells. Since 10% of all your white blood cells are monocytes and 72% of your white
blood cells are granulocytes, at least 80% of your white blood cells accounts for innate immunity.
There’s a lot of interaction between the different cell
types of the immune system.
Several cytokines / growth factors lead to
differentiation of stem cells into different leukocytes.
Pluripotent stem cells in the fetal liver and bone
marrow, known as hematopoietic stem cells (HSCs),
give rise to all lineages of blood cells, including
lymphocytes. The common myeloid progenitor
develops mostly cells for innate immunity, while the
common lymphoid progenitor is more important for
adaptive immunity.
Many nuclear events in lymphocyte development are
regulated by epigenetic mechanisms.
Figure 1 - Innate and adaptive immunity (also natural antibodies are
part of innate immunity)
You can live without adaptive immunity, but not without innate immunity. We can illustrate this by looking at a bacterial infection.
A bacterium divides approximately every 20 minutes in your body. It takes way too long for the adaptive immune system to get
activated and therefore innate immunity is really crucial. Namely, innate immunity is fast and kills by far most microbes (99.9%).
You have both active and passive immunity. Active immunity is conferred by a host response to a microbe or microbial antigen,
whereas passive immunity is conferred by adoptive transfer of antibodies or T lymphocytes specific for the microbe (also occurs
during pregnancy from mother to foetus). Both forms of immunity provide resistance to infection and are specific for microbial
antigens, but only active immune responses generate immunologic memory.
The survival and pathogenicity of microbes in a host are critically influenced by the ability of the microbes to evade or resist the
effector mechanisms of immunity.
Many microbes establish latent, or persistent, infections in which the immune response controls but does not eliminate the
microbe and the microbe survives without propagating the infection.
2
