T Cells

Question 1

T cell receptor

Answer 1

an alpha and beta chain with a variable and constant region

Question 2

all T cells express _

Answer 2

a T cell receptor (TCR)

Question 3

all TCR’s are expressed in association with _

Answer 3

CD3

Question 4

CD3

Answer 4

signal transducer for TCR’s

Question 5

TCR recognizes _

Answer 5

MHC-I or MHC-II proteins

Question 6

alpha chain of TCR is analogous to _

Answer 6

antibody (B cell) light chain

Question 7

beta chain of TCR is analogous to _

Answer 7

antibody heavy chain

Question 8

TCR differences from BCR

Answer 8

does not undergo somatic hypermutation and no affinity maturation

Question 9

MHC Class I structure

Answer 9

an alpha chain with 3 external domains and 1 beta-2 microglobulin domain

Question 10

beta-2 microglobulin domain

Answer 10

no transmembrane region, no cytoplasmic tail, not encoded in MHC (gene)

Question 11

MHC Class II structure

Answer 11

two alpha domains and two beta domains

Question 12

MHC-I peptide binding cleft

Answer 12

2 alpha domains

Question 13

MHC-II peptide binding cleft

Answer 13

1 alpha and 1 beta domain

Question 14

MHC-1 tissue distribution

Answer 14

all nucleated cells and RBC’s in some species (not human)

Question 15

MHC-II tissue distribution

Answer 15

only on antigen presenting cells - macrophages, dendritic cells, B cells, thymic epithelium

Question 16

MHC-I function

Answer 16

presents antigens to CD8+ cells

Question 17

MHC-II function

Answer 17

presents antigens to CD4+ cells

Question 18

MHC-I cells

Answer 18

T cells, B cells, macrophages, neutrophils, other nucleated cells (like hepatocytes)

Question 19

MHC gene structure

Answer 19

contains a DP, DQ, and DR region for class II; contains an HLA-A, HLA-B, HLA-C for class I

Question 20

MHC-II pathway

Answer 20

exogenous antigen –> endocytic vesicle –> peptide production in phagolysosome –> peptide binds MHC-II –> MHC-II presents to CD4+

Question 21

MHC-I pathway

Answer 21

endogenous antigen –> proteasome degrades to peptides –> peptide transport into ER –> peptide binds MHC-I –> presents to CD8+

Question 22

Tap1/Tap2

Answer 22

transports peptides into ER from proteasome in MHC-I pathway

Question 23

adhesion molecules between T cell and target cell

Answer 23

LFA-1 on T cell and ICAM-1 on target cell

Question 24

what binds to MHC?

Answer 24

TCR-CD3

Question 25

thymocyte migration

Answer 25

DN1 in medulla --> DN2 in cortex --> DN3 --> DN4 --> immature double-positive thymocyte --> mature CD8 or CD4 (back in medulla)

Question 26

DN1

Answer 26

CD44+; adhesion

Question 27

DN2

Answer 27

CD44+, CD25+; adhesion and IL-2 receptor

Question 28

DN3

Answer 28

pre-TCR; little of CD44 and CD25

Question 29

DN4

Answer 29

no CD44 or CD25

Question 30

pre-T cell receptor

Answer 30

beta chain rearranges first then alpha chain

Question 31

pre-TCR signaling

Answer 31

stops beta-chain rearrangement and initiates alpha chain rearrangement --> down-regulates CD25 and up-regulates CD4/CD8

Question 32

thymic selection

Answer 32

positive selection of cells whose receptor binds MHC molecules and death of cells that do not --> then negative selection of cell with high affinity for self antigen

Question 33

When does positive selection occur?

Answer 33

at CD4+/CD8+ stage

Question 34

When does negative selection occur?

Answer 34

at CD4+/CD8+ stage and at single positive stage

Question 35

mTEC

Answer 35

medullary thymic epithelial cell; promiscuous gene expression (AIRE)

Question 36

AIRE

Answer 36

autoimmune regulator; transactivator of tissue-specific gene expression which allows negative selection against T cells reactive to tissue-specific antigens