Intro to immune system Flashcards
What are the 4 key principles of the immune system?
- Acts as a barrier
- Identify pathogens
- Kill pathogens
- Remember pathogens
What are the 2 components of the immune system?
1) Innate immune system (all plants, vertebrates and invertebrates)
2) Adaptive immune system (only present in vertebrates)
What is the key difference between the innate and adaptive immune systems?
- Innate immune system provides non-specific recognition with no specific memory response
- Adaptive immune system provides specific recognition with an ability for specific memory response
What is the difference between the specific and non-specific recognition provided by the innate and adaptive immune systems?
Innate = recognizes broad groups of pathogens
Adaptive = recognition of specific pathogens down to a strain level
How does innate immune recognition work?
Innate system identified self and non-self cells using antigens
What are pattern recognition receptors?
PRRs are innate cell receptors that recognise non-self molecules
What is an example of a non-self molecule?
A lipopolysaccharide found on the surface of gram -ve bacteria
What are pathogen associated molecular patterns and where are they found?
PAMPs is the collective term for all of the non-self molecules. They are found on the surface of pathogens.
What must happen in order for an immune response to be generated?
The PRR must bind to the PAMP.
What are the 7 major types of immune cells?
1) Dendritic cells
2) Macrophages
3) Neutrophils
4) Eosinophils
5) Basophils
6) Mast cells
7) Natural killer cells
What type of receptor does a LPS bind to on a dendritic cell/ macrophage?
Binds to TLR 4 (toll-like receptor)
What else can trigger the innate immune system?
Damage associated molecules (things such as DNA or proteins associated with DNA that are ordinarily housed in the nucleus)
What type of receptor detect damage associated molecules?
TLRs and RAGE
Summarize the main 3 roles of innate receptors.
- Recognise conserved structures (LPS)
- Are non-specific so can detect broad groups of pathogens
- Can recognise damage related molecules
How does the innate system contribute to arthritis?
- An inflammatory response is triggered as damage associated molecules are found due to the damaged cartilage.
What two types of lymphocytes form the adaptive immune system?
B lymphocyte
T lymphocyte
What is the function of B lymphocytes?
B lymphocytes secrete antibodies (immunoglobulins)
What are the two types of T lymphocyte?
- CD4+ T lymphocyte (helper T cells)
- CD8+ T lymphocyte (cytotoxic T cells)
What are antigen receptors?
Surface transmembrane immunoglobulins
What antigens are present on T cells and B cells?
B cells have B cell receptors
T cells have T cell receptors
What is the definition of an antigen?
Antigen = any substance that can bind to specific lymphocyte receptors and so induce an immune response
What is epitope?
Complete the sentence…
TCRs and BRCs differ highly in the …(1)… immune system, unlike in the …(2)… immune system in which the antibodies for a certain pathogen will be largely the same across all species.
1) Adaptive
2) Immune
How is diversity created during the formation of antibodies?
Initially, each pre-B cell has the same light chain and heavy chain genes, but these genes have multiple ‘options’
What is the difference between myeloid (RBC) and lymphoid cells (WBC)?
- Myeloid cells are incorporated into the innate immune cells system
- Lymphoid cells form the adaptive immune system
What stem cell do lymphoid stem cells and myeloid stem cells originate from?
- Hemocytoplast stem cells
How are myelocytes and lymphocytes produced?
- Myelocytes are produced via myelopoiesis
- Lymphocytes produced via lymphopoiesis
What are the 5 different types of WBC?
- Neutrophils
- Lymphocytes
- Monocytes
- Eosinophils
- Basophils
(Never let monkeys eat bananas)
Neutrophils make up the largest number of WBCs in most species, what % of WBCs do they make up in dogs, horses and cows?
- 58-85% in dogs
- 52-70% in horses
- 15-30% in cows
What is the lifespan of a neutrophil?
Approx 1-4 days
What do neutrophils look like?
Granulated, multi-lobed nucleus
What is the main role of a neutrophil in immune response?
- Phagocytosis
- Production of anti-microbials
What % of WBC do monocytes make up in dogs/ horses/ sheep?
2-10% in dogs
0-6% in horses and sheep
What happens when a monocyte leaves the blood and enters a tissue?
They develop into macrophages and dendritic cells.
How long are monocytes present in blood?
- Agranulated (no granules)
- Kidney bean shaped nucleus
What is the role of monocytes in the immune response?
- Phagocytosis
- Antigen presentation
- Cytokine release
What are cytokines?
Name 2 examples.
- Small, soluble proteins (peptides + glycoproteins)
- Intercellular messengers of the immune system
- Bind to specific membrane receptors
Examples = interleukins, interferons
What are chemokines?
A subset of cytokines
What is the function of chemokines?
They are chemoattractants so attract the appropriate WBC to the necessary area
What do eosinophils look like?
- Bilobed nucleus
- Heavily granulated
What % of WBC do eosinophils make up in horses/ dogs/ cattle?
Horses = 0-7%
Dogs = 0-9%
Cattle = 0-20%
How long do eosinophils spend in the bloodstream and in tissues?
30 minutes in the bloodstream
12 days in the tissue
What does a rise in eosinophils often indicate?
A helminth or allergy response
What is the role of eosinophils?
- Release inflammatory mediators
- Release alpha helminth molecules
What % of WBC are basophils in dogs + cats/ horses + cattle?
0-1% in dogs and cats
0-2% in horses and cattle
How long do basophils survive for?
3 days
What do basophils look like?
Granulated
Bi-lobed
What is the role of basophils in the immune response?
IgE triggered degranulation
Release histamine (+other mediators)
What are the 3 types of lymphocyte?
- B-lymphocytes
- T-lymphocyes
- Natural killer cells
What do lymphocytes look like?
- Agranulated
- Clear cytoplasm
- Nucleus relatively circular and takes up most of cell
