Adaptive Immune System Flashcards
What determines the effector function of an antibody?
The structure of its constant region (isotype)
Where does differentiation take place respectively for T and B cells?
T cells - Thymus, B cells - fetal liver and adult bone marrow
If a developing B cell`s antibody is found to bind to autoantigen with high affinity, what are the two possible fates for that B cell?
Apoptosis, or further variable gene rearrangement (receptor editing)
Against what cells are developing T cells tested for self-binding?
Thymic stromal cells (if the developing cell binds MHC 1 or 2 on thymic stromal cells it gets destroyed)
What accessory proteins mediate signal transduction when antigen receptor binds antigen in membrane-bound antibodies and TCRs respectively?
Membrane-bound antibodies - IG-a and IG-b, TCRs - the CD3 complex
What is the general structure of antibodies and TCRs respectively?
Antibodies - two identical light chains and two identical heavy chains (each with V and C regions), TCRs - alpha-beta or delta-gamma
How many different types of C regions are there in antibody heavy chains and TCRs respectively?
Antibody heavy chains - 5 different C regions (hence 5 Ig isotypes), TCRs - only one
Regarding IgA, IgG, and IgM, which are secreted multimeric and which are not?
IgA and IgM are secreted multimeric and IgG is not
What is found at the end of each antibody VH and VL chain region?
Three complementarity-determining regions (CDRs). They form the antigen binding site
What are the three types of genes found in antibody and TCR V loci?
Variable, Diversity (not always present) and Joining
Are antibody and TCR V genes downstream or upstream of the genes for the C regions?
Upstream
What allows gene segment joining enzymes to recognize V regions of antibody and TCR genes?
Specific signal sequences adjacent to the V gene segment
What are the two methods of achieving diversity of antibodies and TCRs?
Combinatorial diversity (combining different V D and J regions) and junctional diversity (adding and deleting nuceleotides when joining these regions)
Which is made first when a pro-B cell is creating antibodies, the light chain or heavy chain?
Heavy chain (it forms with a surrogate light chain)
What are the two light chain loci in antibody genes?
Kappa and Lambda
What are the first two types of antibodies formed by a developing B cell?
IgM (first) and IgD (second)
What mediates suppression of heavy and light chain rearrangement in b-cell development?
The heavy and light chains themselves (product inhibition)
Which chain is produced first in t-cell development
Beta chain (in alpha-beta cells) or gamma chain (in delta-gamma cells)
Developing T-cells first express no CD4 or CD8, then both, then only one. What triggers each of these phases?
CD4 and CD8 expression begin together when a proper beta chain is formed. Then one of these ceases when the t-cell can properly bind MHC on thymus stromal cells
