120314 lymphocyte antigen receptors

Question 1

where do T lymphocytes mature?

Answer 1

thymus

Question 2

where do B lymphocytes mature?

Answer 2

peripheral lymphoid organs like lymph nodes and spleen

Question 3

antigen recognition by B cell is mediated by

Answer 3

variabel regions of heavy and light chains of membrane Ig

Question 4

TCR receptor recognition of antigen is mediated by

Answer 4

variable regions of alpha and beta chains

Question 5

how are the 5 different classes of Ig different?

Answer 5

due to constant region differences

Question 6

what are the light chains on a Ig?

Answer 6

kappa or lambda (and doesn’t switch during class switching)

Question 7

avidity

Answer 7

multiple interactions (CD4 and TCR, not just 1 single binding interaction)

Question 8

how does diversity result for TCR and Ig?

Answer 8

gene rearrangement (combinatorial diversity)
junctional diversity (removal or addition of nucelotides)
mix and match of heavy and light chains
somatic hypermutation (over time, Ig binding affinity increases)

Question 9

what is gene rearrangment for the variable region of the heavy chain? (for both Ig Vh and TCR beta)

Answer 9

3 gene segments that recombine during cellular differentiation and maturation (V, D, J)

first recombination event is heavy chain D and J

Question 10

what is gene rearrangement for the light chain of Ig or TCR alpha chain like?

Answer 10

V and J recombine and then VJ recombine with a C segment

Question 11

allelic exclusion

Answer 11

expression of the heavy chain gene product of either the maternal or paternal chromosome, but not both

this ensures clonal specificity

Question 12

pro B cell Ig expression?

Answer 12

none

Question 13

pre-B cell Ig expression?

Answer 13

pre-B receptor

Question 14

immature B cell Ig expression?

Answer 14

membrane IgM

Question 15

mature B cell Ig expression?

Answer 15

IgM and IgD

Question 16

what kind of selection occurs with T cells

Answer 16

positive selection (for reactivity with self MHC plus peptide), then negative selection (to remove thymocytes with high affinity receptors for self peptides)

Question 17

negative selection of T cells in thymus is mediated by?

Answer 17

dendritic cell and macrophages in medulla of thymus

Question 18

how does positive selection occur for B cells?

Answer 18

unclear