antigen presentation and MHC

Question 1

what region of HLA gene codes for class II MHC proteins

Answer 1

D region of HLA gene

Question 2

what regions of HLA gene encode for class I MHC proteins

Answer 2

regions A, B, and C

Question 3

MHC gene expression is

Answer 3

codominant and polymorphic

Question 4

MHC haplotype

Answer 4

total set of MHC genes on each chromosome

inherit one haplotype from each parent

Question 5

how many class I and class II genes does an individual receive

Answer 5

3 different class I and 3 different class II genes from EACH parent
total of 6 different class I and 6 different class II MHC proteins are inherited

Question 6

role of MHC proteins

Answer 6

T lymphocytes only respond to antigen when it is expressed on an antigen presenting cell (APC) in conjunction with MHC proteins

Question 7

narcolepsy gene

Answer 7

HLA-DR2

Question 8

ankylosing spondylitis gene

Answer 8

HLA-B27

Question 9

how to increase success of long term graft survival in organ transplantation

Answer 9

match HLA types

immunosuppressive drugs

Question 10

why is it a problem that RBCs don’t have MHC molecules

Answer 10

in malaria, when RBCs are infected, they cannot alert cytotoxic T cells that they are infected

Question 11

beta 2 microglobulin is required for

Answer 11

cellular expression of alpha chain in class I MHC
without beta 2, can't get MHC I to cell surface

Question 12

where are MHC proteins

Answer 12

surface of all nucleated cells

not on erythrocytes (no nucleus) or corneal epithelial cells

Question 13

where are MHC class I proteins

Answer 13

surface of all nucleated cells

not on erythrocytes (no nucleus) or corneal epithelial cells

Question 14

where are MHC class II proteins

Answer 14

surface of APCs (dendritic cells, macrophages, and B lymphocytes)

Question 15

polymorphic

Answer 15

multiple variants of each gene exist in population

Question 16

polygenic

Answer 16

multiple variants of one gene within an individual’s genome

Question 17

structure of class I MHC

Answer 17

alpha and beta chains
alpha is longer than beta
beta 2 microglobulin is required for cellular expression of alpha chain
cleft accommodates peptides that are 9-11 amino acids in length

Question 18

structure of class II MHC

Answer 18

alpha and beta chains
equal in length
cleft accommodates peptides that are 10-30 amino acids in length (because cleft is open at ends)

Question 19

MHC restriction

Answer 19

CD8+ T cells recognize only protein fragments in cleft of class I MHC
CD4+ T cells recognize only protein fragments in cleft of class II MHC

Question 20

linear determinants

Answer 20

T lymphocytes can only recognize linear determinants because only linear can be processed by MHC proteins

Question 21

gamma interferon

Answer 21

T lymphocyte is activated by APC
T cell produces gamma IFN
gamma IFN induces higher levels of class II MHC on APCs
gamma IFN also induces expression of class II MHC on epithelial, glial, mesenchymal, and vascular endothelial cells to aid in T cell activation