Adaptive Immune System

Question 1

What determines the effector function of an antibody?

Answer 1

The structure of its constant region (isotype)

Question 2

Where does differentiation take place respectively for T and B cells?

Answer 2

T cells - Thymus, B cells - fetal liver and adult bone marrow

Question 3

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?

Answer 3

Apoptosis, or further variable gene rearrangement (receptor editing)

Question 4

Against what cells are developing T cells tested for self-binding?

Answer 4

Thymic stromal cells (if the developing cell binds MHC 1 or 2 on thymic stromal cells it gets destroyed)

Question 5

What accessory proteins mediate signal transduction when antigen receptor binds antigen in membrane-bound antibodies and TCRs respectively?

Answer 5

Membrane-bound antibodies - IG-a and IG-b, TCRs - the CD3 complex

Question 6

What is the general structure of antibodies and TCRs respectively?

Answer 6

Antibodies - two identical light chains and two identical heavy chains (each with V and C regions), TCRs - alpha-beta or delta-gamma

Question 7

How many different types of C regions are there in antibody heavy chains and TCRs respectively?

Answer 7

Antibody heavy chains - 5 different C regions (hence 5 Ig isotypes), TCRs - only one

Question 8

Regarding IgA, IgG, and IgM, which are secreted multimeric and which are not?

Answer 8

IgA and IgM are secreted multimeric and IgG is not

Question 9

What is found at the end of each antibody VH and VL chain region?

Answer 9

Three complementarity-determining regions (CDRs). They form the antigen binding site

Question 10

What are the three types of genes found in antibody and TCR V loci?

Answer 10

Variable, Diversity (not always present) and Joining

Question 11

Are antibody and TCR V genes downstream or upstream of the genes for the C regions?

Answer 11

Upstream

Question 12

What allows gene segment joining enzymes to recognize V regions of antibody and TCR genes?

Answer 12

Specific signal sequences adjacent to the V gene segment

Question 13

What are the two methods of achieving diversity of antibodies and TCRs?

Answer 13

Combinatorial diversity (combining different V D and J regions) and junctional diversity (adding and deleting nuceleotides when joining these regions)

Question 14

Which is made first when a pro-B cell is creating antibodies, the light chain or heavy chain?

Answer 14

Heavy chain (it forms with a surrogate light chain)

Question 15

What are the two light chain loci in antibody genes?

Answer 15

Kappa and Lambda

Question 16

What are the first two types of antibodies formed by a developing B cell?

Answer 16

IgM (first) and IgD (second)

Question 17

What mediates suppression of heavy and light chain rearrangement in b-cell development?

Answer 17

The heavy and light chains themselves (product inhibition)

Question 18

Which chain is produced first in t-cell development

Answer 18

Beta chain (in alpha-beta cells) or gamma chain (in delta-gamma cells)

Question 19

Developing T-cells first express no CD4 or CD8, then both, then only one. What triggers each of these phases?

Answer 19

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