L3 Introductory to immunology Flashcards
Adaptive immunity
They do not have recognitive immunity system.
General:
-Veterbrates and invertabrates
-Between cephlapods and jawless fish
-The 1st lymphocyte type cell and igG molecule in jawless fish
-Sharks and fishes have a thymus and MHC
Birds have bursa
Mamals: Differences in MHC, Tcells and Bursa
Innate vs adaptive
Can be distinguished by: Innate/Adaptive
How quickly the response: Minutes-hours/Days
Specificity : Limited and fixed/Highly diverse, improve overtime
Response to repeat infection: Same each time/rapid and effective with subsequent exposure
Major components: Barriers eg skins/T-cells and B-cell
Adaptive immunity
- The importance of SELF
- Major histocompatilbility compex (MHC)
- Dendric cells/Antigen presenting cells
- Tcells
- B cells and plasma cells
- Antibodies
- Memory
Why detect a self molecule on the cell?
Important in adaptive immunity, its a simple way of spying on the inside of the cell from the outside.
i.e it reviews wheter a cell is healthy or not.
MHC protein
A receptor/antigen binding site
Genetically diverse glycoproteins
Cell membranes
Two versions: MHC class 1 - all nucleated cells in vetebrates MHC class 2- professional APC
Importance of MHC
Display self class 1 to demonstrate cell is healthy, if not, tumour/mutation/infection. To display foreign peptide in class 1 to show that the cell is infected and activate T-cytotoxic cells To display a self peptide in class 1 and 2 to test T-cells for autoreactivity. To display a self peptide in class 1 and 2 to maintain TOLERANCE to self-proteins. To display a foreign peptide in class 2 to show the body is infected and activate T-helper cells.
MHC structure
Multi-domain proteins.
Antigen presenting cells (APC)
Cell that present foreign (normal and professional) Professional: Dendritic cells, express MHC class 2 Other nucleated cells: express class 1
Types of APC
Antigen presenting cell
Dendritic cells
Macrophage
B cell
Dendritic cells
Makes contact with pathogens.
It senses foreign particles, it digests foreign bodies, and presents it. Digest and ingest.
Class 2 MHC
Generation of diversity (lymphocyte)
immune system is invested in generating a set of cells that have receptors towards antibodies, where they essentially makes antibodies and cells against every possible antigens u can get.
Each lymphocyte (cellular level), has specificity, binds to 1 peptide but with many receptors.
Diagram:
Stem cell > primary lymph organs > Synthesis antibodies > deletion > Amplification to used antigen > some are kept as memory cells.
Lymphocytes
Principle players in adaptive immune system
20-40% of WBC
99% of lymph cells
Approx. 1 trillion circulate
3 types
B cells
T cells
NK cells
B-cells
Mature in the bone marrow
Synthesis and display B-cell receptor
Each B cell has a unique antibody
Activated B cells become plasma cells, last 1-2 weeks
T-Cells
Mature in Thymus
Receptor is a T-cell receptor
T cells recognises foreign antigen bound to an MHC.
The specificity changes depending on the class of MHC.
2 Types:
Helper T cells CD4- produce cytokines
Cytotoxic T cells CD8- kill cells, apoptosis, digestive secretion
Ratio is 2:1 respectively.
If T-cell binds to an MHC class 1, the T-cells adapt to CD8 form, where it kills the cell.
If T-cells binds to an MHC class 2 - foreign inside it. but involved in phagocytose, its likely foreign is somewhere else. Hence it adapts to CD4 cells, produce cyotkines to help it. Or produce antibody
T and B lymphocyte
Synthesis: Bone marrow/Thymus
Recognition: Antibody/T cell receptor
Secreted: Antibody / Cytokines
Disposal: Antibody / some are Toxic
MHC restriction
2 signals produce activation of T-cells
Antibody and TcR (tcellreceptor)
TCR are very similar to antibodies
Collaboration between innate and adaptive immunity
Dendritic cells go into the lymph nodes, where they interact with lyphocytes, and they present to both T and B cells.
Activation occures
Proliferation occurs of the correct specificity, that can go into the lymph node into the blood, which are specific T/B cells with the right antibody that can fight that infection.
Not all the T and B cells go into the blood stream, some remain, which are speficified up to 70 years.
