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Flashcards in 2. Immunogenetics Deck (32)
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1

components of the BCR

surface Ig and two invariant chains (Igalpha and Igbeta)

2

components of the TCR

alpha:beta heterodimer (receptor), CD3 chains (epsilon: gamma and zeta:zeta chains) (signaling)

3

heavy chain recombination for b cells is analogous to what structure in t cells

beta chain of t cells : heavy chain of b cells

4

somatic hypermutation only occurs in

TCRs

5

light chain (alpha chain of T cells) undergoes

V to J rearrangement d

6

heavy chain (beta chain of T cells) undergoes

D to J rearrangement followed by V to DJ rearrangement

7

recombination signal sequences direct

VDJ recombo through
1) giving recognition enzymes a place to cut and rejoin DNA
2) ensuring gene segments join in correct order

8

enzyme responsible for recombining V,D, and J segments with the help of RAG-1 and -2

V(D)J recombinase

9

RAG does what

Recombination activating genes - helps V(D)J recombinase do its thing by binding to hairpin loop to get cut off

10

enzyme that catalyzes the random polymerization of nucleotides without the need for a template

Terminal deoxyribonucleotidyl transferase adds N nucleotides
TdT (looks like TNT)

11

as opposed to N nucleotides, P nucleotides are added in

an asymmetric manner to the ends of cleaved hairpins that serve as templates

12

the process of inserting nucleotides between the D and J segments in the third hypervariable region is known as

junctional diversity

13

in addition to recombination, receptor chains possess another form of combinatorial diversity in the form of

joining of receptor chains - two receptor chains are needed to make the Ag binding site

14

CD43+, CD19+, CD10+ cells that also express RAG and TdT

Pro-B cells - forming receptor still

15

b cell that possesses a surrogate light chain

Pre-B cell B220lo, CD43+

16

mature naive B cells express IgM and IgD on their cell surface because these two products are a result of

alternative mRNA splicing of the transcript for heavy chain

17

provide signals for naive B cell maturation

Stromal cells
express VCAM (:VLA-4 on lymphoid progenitor)
Express SCF (:Kit on Pro-B)
Express I-L-7 (late pro-b to pre-B)

18

although t cells mature in the thymus, they originate in

the bone marrow as t cell precursors

19

double negative T cells exist in what layer of the thymus

subscapular region

20

double positive t cells exist in what layer of the thymus

cortex

21

maturation into single positive t cells occurs in what layer of the thymus

cortico-medullary junction

22

thymic stromal cells are unique in their ability to

express both HLA classes - helping in the maturation of both CD4 and CD8 T cell populations

23

stage defined by surrogate alpha/beta chain

Pre-T

24

in general, ______ Ag recognition is selected for and _______ Ag recognition is selected against

weak
strong

25

immature b cells that recognize multivalent self Ag are

induced to perform apoptosis

26

B cell light chains can undergo the unique process of ______ if they are self-reactive in order to potentially rescue the clone

light chain receptor editing
if this fails, the b cell will undergo apoptosis

27

two checkpoints in b cell development `

Pre-B cell receptor - if there is no receptor ==> apoptosis
After light chain rearrangement - if there is no receptor ==> apoptosis

28

double positive t cells undergo 2 selection events

1) positive selection ensures only cells with TCRs that bind appropriately to MHC molecules on cortical epithelial cells survive
2) negative selection of cells that recognize self

29

after this selection, t cells may still react with self Ag, but they are MHC restricted

positive selection

30

after maturation to single positive T cell, they will

migrate out of the thymus via blood venules