Adaptive Immunity Flashcards
What are antibodies?
BCRs that interact with antigens.
After activation, B cells secrete soluble forms of BCRs as Abs
Ab = BCR binding moiety
How are antigen specific receptors determined?
Specificity and diversity determined by genes.
Rearrangements during development of B cells in marrow, T cells in thymus
What is the structure of an antibody?
4 polypeptide chains with 2 antigen binding sites
What are antigen specific receptors?
Antibodies & TCRs
What is the structure of TCRs?
2 polypeptides and 1 antigen binding site
Where are TCRs found?
They are membrane bound on the cell’s surface
What is another name for antibody?
Gamma globulins = Igs
How are T cells activated by antigens?
Antigens are processed and broken into smaller fragments that are then in the MHC on APCs to activate T cells
What is the difference between MHC class I and II presentation?
MHC class I presents Ag to CTLs MHC class II presents Ag to Th cells
What is clonal selection?
The core concept of adaptive immunity.
Each B and T cell has unique antigen specificity which is established prior to contact with the antigen. The antigen selects the cell type that will undergo clonal expansion.
What happens during the primary immune response?
Occurs as result of first contact with antigen.
Responding cells are naive B and T cells.
First Ab produced is IgM with small amount of IgG.
Primary response occurs mainly in lymph nodes and spleen.
Clonal selection
Antibody levels decline quickly.
What happens during the secondary immune response?
Occurs as a result of a second or subsequent exposure.
Responding cells are memory cells.
Shorter duration to establish immunity
Mainly IgG produced, although others in smaller amounts.
Antibodies have greater affinity and last longer