Major Histocompatibility Complex

Question 1

what do B cells need to switch antibody class, make high affinity antibodies, or become memory B cells?

Answer 1

help from T cells
to become activated through the BCR binding to the extracellular antigen

Question 2

are antibodies generally effective against intracellular pathogens?

Answer 2

no

Question 3

what cells in adaptive immunity destroy infected host cells?

Answer 3

cytotoxic T cells

Question 4

when will a cytotoxic T cell interact with an intracellular antigen?

Answer 4

when a fragment of the antigen (antigenic peptide) is on the surface of a host’s cell bound to a major histocompatibility complex

Question 5

the phenomenon of T cells recognizing an antigen only in association with self-MHC molecules is called ___________

Answer 5

MHC restriction

Question 6

why are two classes of MHC molecules needed?

Answer 6

Tc cells are MHC class I-restricted
Th cells are MHC class II-restricted

Question 7

the MHC acronym for dogs is ___ and the acronym for horses is ___ and the acronym for caprines is ___

Answer 7

DLA
ELA
CLA

Question 8

each MHC class I molecule consists of a ________________________________ and a ____________________

Answer 8

large transmembrane glycoprotein alpha chain
much smaller beta-2 microglubulin

Question 9

what are the domains of the alpha chain? which ones are variable and which ones are constant?

Answer 9

alpha-1: variable
alpha-2: variable
alpha-3: constant

Question 10

what forms the peptide binding groove or peptide binding cleft in MHC I?

Answer 10

parts of the alpha-1 and alpha-2 domains

Question 11

is the peptide binding groove/cleft of the alpha chain closed at both ends or open at both ends?

Answer 11

closed at both ends so can only fit peptides 8-10 amino acids long

Question 12

the amino acid differences between the MHC products are confined principally to the sites in the _______________

Answer 12

peptide binding groove where the antigenic peptide binds

Question 13

what glycoprotein do cytotoxic T cells express on their surface and what domain does it bind to?

Answer 13

CD8 binds to the alpha-3 domain of MHC I

Question 14

what is the beta-2 microglublin?

Answer 14

invariant polypeptide that provides stability to the MHC class I molecule
without it, alpha chain does not express on cell surface

Question 15

what makes up the MHC class II molecule?

Answer 15

an alpha and a beta chain, each with two domains

Question 16

what folds into the peptide binding groove or cleft in the MHC class II molecule?

Answer 16

alpha-1 and beta-1 domains (these are the polymorphic ones)

Question 17

what is the peptide binding groove/cleft like in the MHC class II molecule?

Answer 17

open at both ends
large peptides fit: 12-20 amino acid residues

Question 18

what glycoprotein do helper T cells express on their surface to bind the beta-2 domain of MHC II?

Answer 18

CD4

Question 19

on what cells are MHC class I molecules expressed?

Answer 19

almost all nucleated cells
most highly expressed on lymphocytes and specialized antigen presenting cells

Question 20

MHC class II molecules are expressed on __________________________

Answer 20

only specialized antigen presenting cells

Question 21

what molecules play a role in T cell development in the thymus and T cell activation in the secondary lymphoid organs?

Answer 21

MHC proteins

Question 22

what are the undesired functions of MHC molecules?

Answer 22

transplant rejection
certain autoimmune or inflammatory diseases

Question 23

when there are no foreign antigens present, what happens with MHC class I and II peptide binding grooves?

Answer 23

they are loaded with peptide fragments derived from the body’s own proteins: self-antigens

Question 24

when is the presentation of self-antigens important?

Answer 24

development phase of T lymphocytes in the thymus

Question 25

true/false: the peptide binding groove is formed by alpha-1 and alpha-2 of MHC class I

Answer 25

true

Question 26

true/false: expression of MHC class I, but not MHC class II molecule, is much greater in dendritic cells than in macrophages

Answer 26

false: both expressed at greater rate on dendritic cells than on any other antigen presenting cells

Question 27

what does CD4 bind with?

Answer 27

beta-2 domain of MHC class II molecules