Immunology - Adaptive Immunity Flashcards
Describe adaptive immunity
Specific or not specific?
Fast?
Activation needed?
Memory?
Which are the main cells involved?
Specific
Slow
Need activation
Have memory
Killing usually antibody mediated
Main cells are T & B (+ plasma) cells
Where are T cells produced and mature?
Produced in Bone marrow, mature in thymus
What is the process called that chooses which T cells are good?
Thymic tolerance
What happens in positive selection?
T cells tested to see if they recognize thymus MHCs (major histocompatibility complex) (1+2), they are then selected for
What happens in negative selection?
If T cells produce immune response, selected against
What happens in allocation?
If T cells interact with:
MHC 1 = CD8+ cells (Tc)
MHC2 = CD4+ cells (Th)
CD8+ (Tc) cells
What do they interact with?
Function?
Interact with MHC 1
Direct cytotoxic killing
How do CD8+ cells kill? 2 ways?
- Perforin secretion (mediated by granzyme B)
- Express FasL - activates caspases
What’s a naive T cell?
T cell never encountering antigen (not treated in thymus yet)
Who do CD4+ (Th) cells interact with?
What are the 2 types of Th cells?
Interact with MHC 2
Th1 & 2
What do Th1 cells do?
IFN-Y
Activate NK cells and macrophages (increase innate response)
What do Th2 cells do?
Activate B cells to differentiate into plasma cells (increase adaptive response)
Where do B cells produce and mature?
What happens to B cells that launch immunity to themselves?
Bone marrow
Apoptosis
How is Th2 activated? What does it release?
Activated by APC and MHC 2 interaction (eg. With dendritic cell)
Th2 release:
IL4 which induces B cell proliferation (clonal expression)
IL5 which induces B cell differentiation into plasma cell - produce (GAMED) Ig
Ig’s act vs specific pathogen present but if need arises?
A.I.D
Activation induced cysteine deaminase does 2 things
What can A.I.D do?
- Produce pant mutations in Ig as ‘evolutionary measure’ - somatic hyper mutation
- Induce class switching (mutate GAMED to another isotope)
IL4 - promotes class switching to IgA
IL5 - promotes class switching to IgE (allergic response)
Describe IgG
Most abundant Ig in blood
Key in 2^ immune response (marker of immune memory), very specific
IgG 1,2,3,4 subtypes
Describe IgA
Most abundant Ig in total body
Found on mucosal lining & in colostrum/breast milk
Forms DIMER
Describe IgM
First Ig released in adaptive response
Less specific
Forms pentamer
Describe IgE
IgE activates mast cells and basophil degranulation in T1 hypersensitivity
Anaphylaxis
Describe IgD
Unknown function
Presumed to be B cell receptor components
What does MHC stand for?
Where are they found?
What are they also?
Major histocompatibility complex
On chromosome 6
HLA (human leukocyte antigen) molecules
What are the 2 functions of MHCs?
- Interactions with T cells
Th (CD4+) interact with MHC2 - on APCs
Tc (CD8+) interact with MHC1 on all nucleated cells (not RBC) - Confer susceptibility to inherited autoimmune diseases
HLAB27 - spondyloarthropathies
HLADR2DQ3 - T1DM
HLA DQ2/DQ8 - coeliacs
