L14 Adaptive Immunity Flashcards
Key features of innate immunity
Limited specificity
Found in all tissues especially at barrier sites
Acts quickly following infection
Limited memory
Key features of adaptive immunity
Specific for particular proteins/ antigens
Mainly found in lymphoid organs
Takes 5-10 days to get going
Long lived immune memory
Types of adaptive immune cells and what do they do
B and T cells
Cells that specifically recognise antigens viaspecialised surface receptors
What do B cells receptors bind to
native proteins/ antigens
(no accessory cells required)
What do T cells recognise
Processed antigen presented on MHC molecules on the surface of antigen presenting cells
CD4 T cells see longer peptides in MHC class 2 molecules
CD8 T cells see short peptides in MHC class 1 molecules
Where are adaptive immune cells generated and activated
Generation: primary lymphoid organs (thymus and bone marrow)
Activation: secondary lymphoid organs (lymph nodes and spleen)
Steps in adaptive immune response
T cell activation
T cell differentiation
T cell effector stage
What do the types of adaptive immune cells do
CD4+ T cell - coordinate immune response
CD8+ T cell - kill infected cells
B cells - make antibody to clear up pathogen
What types of Antibodies are there
IgM, IgG, IgE, IgA
What 3 ways can antibodies protect the host
1 Neutralise the pathogen and stop it infecting host cells
2 Activate complement to enhance the immune response
3 Enhance phagocytosis by binding to receptors on phagocytes
How do CD4 T cells recognise antigens
CD4 T cells recognise peptides presented on MHCII molecules
MHCII is mainly expressed by professional antigen presenting cells
How do CD8 T cells recognise antigens
CD8 T cells recognise peptides presented on MHCI molecules
MHCI is expressed by all nucleated cells
How do CD4 T cells support other immune cells
Help CD8 T cells make strong responses: via DCs and soluble molecules
Help B cells generate high affinity antibodies
Activate macrophages to kill phagocyted pathogens more effectively
CD8 T cells are cytotoxic cells, what does this mean
They kill infected cells at site of infection
CD8 T cells find infected cells and trigger apoptosis
When can memory T and B cells act quickly
Upon re-infection
