L 13 Antigen Processing and Presentation

Question 1

exogenous antigen processing pathway

Answer 1

polypeptides from endosomes or phagosomes, HLA Class II and recognized by CD4+ Helper T cells

Question 2

endogenous antigen processing pathway

Answer 2

polypeptides derived from the cells own machinery, HLA Class I and recognized by CD8+ CTLs

Question 3

genetic polymorphisms of MHC genes

Answer 3

different multiple stable forms or alleles

Question 4

HLA Class I

Answer 4

monomer (alpha-1, -2, -3) and an associated Beta2-microglobulin

Question 5

antigen binding site for HLA Class I

Answer 5

between alpha-1 and -2

Question 6

Beta2-microglobulin function

Answer 6

associates with HLA and is critical to maintain active conformation

Question 7

CD8+ binding on HLA Class I

Answer 7

alpha-3

Question 8

Cytoplasmic tail of HLA Class I

Answer 8

1 cytoplasmic tail that transmits signal once T cell is bound

Question 9

HLA Class II

Answer 9

dimer of (alpha and beta chains) each with own cytoplasmic tail for signal transmission

Question 10

Antigen binding site for HLA Class II

Answer 10

between Alpha-1 and beta-1

Question 11

CD4+ binding on HLA Class II

Answer 11

binds the beta-2 domain, critical for T help cell activation

Question 12

ER synthesizes

Answer 12

HLA Class I and II and Ii molecule

Question 13

Invariant chain (Ii)

Answer 13

stabilizes unbound HLA Class II during synthesis, blocks endogenous binding of “self” molecules

Question 14

CLIP

Answer 14

small peptide remnant of the Ii molecule that remains in the Ag binding site of the HLA Class II molecule

Question 15

peptide exchange

Answer 15

CLIP peptide in the Ag binding sit of the HLA Class II molecule swaps with the Ag

Question 16

HLA-DM

Answer 16

enzyme that catalyzes the peptide exchange

Question 17

Cells that constitutively express HLA Class II

Answer 17

dendritic cells of spleen and lymph nodes, thymic epithelial cells and B cells

Question 18

Cells that can be induced to express HLA Class II

Answer 18

tissue-based macrophages and endothelial cells in response to inflammatory stimuli

Question 19

Ubiquitin

Answer 19

Targets endogenously generated foreign antigens for proteolysis

Question 20

proteosomes

Answer 20

degrade ubiquitin tagged proteins

Question 21

Transporters of degraded peptides to RER

Answer 21

TAP-1 TAP-2

Question 22

What proteins are released from HLA Class I molecules when Ag’s bind

Answer 22

calnexin and calreticulin; help fold the HLA Class I molecule and hold Beta-2 micro globulin in place

Question 23

HLA class I molecules are constitutively expressed on

Answer 23

all nucleated cells; important because any cell can become infected or malignant

Question 24

Cross presentation

Answer 24

exogenous peptides are presented to HLA Class I molecules, likely due to debris that escapes endosomes

Question 25

Lipid recognition

Answer 25

CD1 family; similar in structure to HLA Class I (beta2-microglobulin) similar in function to HLA Class II (endosome)

Question 26

CD1 molecules are found on

Answer 26

B cells and dendritic cells

Question 27

CD1 may activate

Answer 27

CD4+ T helper cells, CD8+ CTL, or NK cells