Adaptive Immunity: Antigen Recognition

Question 1

repertoire

Answer 1

the total number of distinct lymphocyte clones

Question 2

T-Cell negative selection

Answer 2

whr: Thymus
wh: double negative T cells whose receptors strongly recognize MHC-selfpeptide complexes are eliminated.
wy: to prevent autoimmunity maybe?

Question 3

T-Cell positive selection

Answer 3

whr: thymus
wh: T-cells only recognize peptides served on an MHC platter. T cells that fail to recognize MHC presented peptides die
wy: to eliminate useless T-cells

Question 4

pro-T cells

Answer 4

aka: double negative T cells
whr: thymus
wh: cells that lack either CD4 or CD8 receptors. they mature due to IL-7

Question 5

aka: pro t-cell

Answer 5

double negative cell

Question 6

T-lympohcyte maturation
1. 
2. 
3. 
4.

Answer 6

1. Stem cell, bone marrow
2. Pro T-Cell (Double Negative T cell), Thymus
   * recombination of Beta chains
   * recombination of alpha chains
3. PreT- Cell (Double Positive T Cell), Thymus
   * positive and negative selection, Thymus
4. Mature CD4 or CD8 cell, Thymus

Question 7

aka: pre T-cell

Answer 7

double positive cell

Question 8

Steps of B-Cell Maturation
1.stem 
2. 
3. 
4.
5. mature B cell
*figure 4-13

Answer 8

1. stem cell
2. Pro-B Cell
   * rearrangement: VJD, heavy chain
3. Pre-B Cell
   * allelic exclusion
   * rearrangement: light chain
4. Immature B cell
5. Mature B Cell

Question 9

pre-BCR complex

Answer 9

a. heavy chain
b. surrogate light chain
c. Ig alpha and Ig beta signaling molecule

1. causes allelic exclusion
2. triggers light chain recombination

Question 10

receptor editing

Answer 10

an immature B-cell may react with an antigen strongly and reactivate VDJ recombinase to edit the VJ region of its light chain

Question 11

follicular B cells

Answer 11

mature B-lymphocytes found in lymph node follicles

Question 12

marginal-zone B cells

Answer 12

mature B-lymphocytes found in splenic follicles

Question 13

B-1 lymphocytes

Answer 13

mature B-lympohcytes found in the peritoneal cavity and lymph tissue. They may arise from different progenitors than follicular and marginal-zone B cells

Question 14

immature B lymphocytes

Answer 14

have survived heavy chain and light chain recombination as well as allelic exclusion

they lack coexpression of IgM and IgD

Question 15

combinatorial diversity

Answer 15

diversity of antigen receptors based on how V,D, and J gene segments recombine. Limited

Question 16

junctional diversity

Answer 16

unlimited diversity of antigen receptors produced by 3 events

1. exonuclease activity
2. TdT
3. P-nucleotides

Question 17

TdT

Answer 17

an enzyme in lymphocytes that catalyzes random addition of nucleotides to junctions between V,D, and J segments

Question 18

P-nucleotides

Answer 18

nucleotides that are randomly added between before double stranded breaks are repaired during VDJ recombination

Question 19

V-gene segment

Answer 19

variable region segments encoding part of antigen receptors (100 or so)

Question 20

C-gene segments

Answer 20

constant regions

Question 21

D-gene segments

Answer 21

only found in Ig Heavy chain and TCR Beta Chain

diversity segment sequences

Question 22

Rag-proteins 1&2

Answer 22

parts of VDJ recombinase that recognize flanking regions of DNA and initiate recombination

Question 23

What is the sequence of VDJ joining

Answer 23

in heavy chains: 
1. D joins with J
2. V joins with DJ segment
in light chains: 
1. V joins directly with the J segment
*C-region is spliced to join the VDJ