L1- Introduction Flashcards
Immune system Evolution:
Name the organisms whose immune systems are based on phagocytic cells only
sponge - porifera
Starfish - Echinoderms
Tunicate - Primitive chordates
Immune system Evolution:
Name the organisms whose immune systems are based on phagocytic cells and appearance of lymphocytes
Jawless fish - lamprey
Immune system Evolution:
Name the organisms whose immune systems are based on phagocytic cells and lymphocytes that separate into B cells and T cells
Sharks- cartilaginous fish Bony fish Frog - amphibians snake - reptiles Duck - birds humans - mammals
In mammals, where is the centre of haematopoiesis?
The bone marrow
What is RAG?
Recombinant activated genes.
RAG mediated immunity is incredibly important in mammals
In mammals, what % of immune cells are in the gut
70%
Particularly dendritic cells
Where do young T cells travel to mature?
The thymus
What cells do the spleen synthesise?
B antibodies (about 50% are monocytes)
What type of cells are dendritic cells?
Phagocytic and antigen presenting cells
What is the number of different cells in the immune system?
10 to the power of 12
How many cell types are involved in the immune system?
> 10
What is the number of cells in the brain?
10 to the power of 11
What is the number of different cells in the brain?
2
Where is the immune system?
- in the blood
- in the lymphatics and lymph organs
How much of the blood is plasma?
55%
How much of the blood is WBC
1%
How much of the blood is RBC?
44%
What is serum?
plasma without clotting factors
Where do WBC circulate?
Within the blood
Where does cellular interaction of immune cells occur?
In the lymphatic system (not in the blood)
Some WBC and a bit of plasma leave capillaries in tissues
As overleaf
What does the circulation of WBC and plasma through interstitial space/tissues and back via lymphatics to lymph nodes allow?
Surveillance of tissues for foreighn molecules and pathogens
What do neutrophils, basophils and eosinophils do?
Attack a variety of pathogens by phagocytosis (phagocytic cells) or with anti-microbials and histamine released after degranulation
What do plasma cells (derived from B-lymphocytes) do?
Secrete large amounts of antibodies
What is the role of monocytes and macrophages?
Phagocytose (phagocytic cells) and regulate many aspects of innate and adaptive immune responses
What is the role of B and T-lymphocytes
Orchestrate the adaptive immune response and provide immunological memory
What does the immune system do?
It discriminates between self and non-self and protects us against pathogens bacteria, fungi, parasites and viruses.
What molecules are pathogens usually covered in to have its own molecular signature (antigens)?
PAMPS
What do immune cells have to recognise PAMPS?
Immune cells have PRR that recognise the pathogen PAMPS
What are an example of PAMPS recognised by the innate immune system PRR?
Nucleic acid - CpG motif DNA (bacteria), ssRNA (viruses), dsRNA (viruses)
Conserved stress proteins - heat shock proteins (bacteria)
Conserved surface proteins - Flagellin (bacteria)
Cell wall components - Peptidoglycan (bacteria), LPS (G+ bacteria) and Galactomannans (fungi)
Name the soluble receptors
- Natural antibodies
- Complement
- Pentraxins
- Collectins
- Ficolins
(all PRRS)
Name the cell receptors
- TLR
- NOD-like receptors
- RIG-like receptors
- C-type lectin-like receptors
- Scavenger receptors
- N-formyl met-leu-phe receptors
Describe the Innate immunity
- Descriminate self and non-self
- Receptors encoded in germline
- Typically recognise structures common to different microbes
Binding of PAMPS to PRR on phagocytic cells leads to innate immune response, which is fast and does not require immunological memory.
Describe adaptive immunity
- Can discriminate self and non-self
- Receptors encoded by gene recombination - massive diversity
- Typically recognise structures unique to different microbes
Adaptive is slower than innate and is activated by a cascade of chemical signals from site of infection, and physical interactions betweenphagocytic cells of innate immune system known as DENDRITIC cells that migrate from site of infection into the lymphatic system to activate lymphocytes
Cytokines and chemokines are released where?
At the site of infection by resident macrophages and recruit neutrophils from the bloodstream leading to localised inflammation (look at picture)
Lymphocytes and adaptive immune response - T-lymphocytes and B-lymphocytes:
What they express?
A vast repitoire of recognition receptors:
B-lymphocytes express antibodies as B cell receptors (BCRs) while T-lymphocytes express T cell receptors (TCRs).
During adaptive immune response, B and T lymphocytes with receptors specific for particular pathogen molecules proliferate. Clonal selection and expansion forms the basis of protective immunity and immunological memory through which the body is protected against future attack.
