MHC

Question 1

B cell receptors recognize

Answer 1

Free antigen

Question 2

T cell receptors recognize

Answer 2

antigen presented by MHC on cell
surface

Question 3

Antigen processing

Answer 3

Antigen proteins digested in the cells.

Question 4

Three MHC classes (I, II and III).

Answer 4

MHC I and II - related by structure and function. Class III is very different- (complement and TNF, lymphotoxin)

Question 5

MHC class I – peptide interaction

Answer 5

MHC I found on all nucleated cells
Present peptides to CD8 T cells
Short peptides- 8-10 aa most are nonamers (9)
Peptides derived from the cell- endogenous antigens
Viruses or proteins from the cell

Question 6

MHC class II – peptide interaction

Answer 6

Restricted expression- on antigen presenting cells (APC), B cells, dendritc cells, monocytes, macrophages
Present peptides to CD4 T cells Longer peptides- 13-18 aa
Peptides from antigens taken up by the cell- exogenenous antigens
Groove is open on both sides- allowing some longer peptides to
bind

Question 7

Human leukocyte antigen complex

Answer 7

HLA

Question 8

MHC class III.

Answer 8

Diverse set of proteins, some of them are immune system proteins, do not present antigens to T cells. Complement components, and tumor necrosis factors

Question 9

Non-classical
MHC genes:

Answer 9

E,G,F Restricted tissue or developmental stage expresssion, varied roles in immunity. DM- role in
peptide loading of MHC class II. HLA G important for protect fetus from beeing rejected by mother

Question 10

MHC genes

Answer 10

highly polymorphic

Question 11

Variations affect antigen-binding part MHC

Answer 11

(polymorphic antigen binding site)

Question 12

Transplant rejections

Answer 12

are caused by differences at MHC locus between donor and recipient

Question 13

histoincompatibility

Answer 13

the property of having the same, or sufficiently similar, alleles of a set of genes called human leukocyte antigens (HLA), or major histocompatibility complex (MHC).

Question 14

Foreign peptides in MHC class I

Answer 14

targetet by CD8+ cytotoxic T cell-mediated destruction.

Question 15

Target cell

Answer 15

The cell with foreign peptide

Question 16

MHC class II molecules display

Answer 16

peptides from the extracellular sources Specialized cells have this function (APC, antigen-presenting cells)

Question 17

CD4+ TH cells are activated

Answer 17

help CD8 T etc

Question 18

pAPCs

Answer 18

Professional antigen presenting cells

Question 19

Professional antigen presenting cells

Answer 19

dendritic cells, macrophages, B lymphocytes

Question 20

dendritic cells

Answer 20

Express high levels of MHC class II molecules and have co-stimulatory activity all the time, and quickly activate the T cells

Question 21

Macrophages

Answer 21

need to be activated to express MHC class II molecules and costimulatory molecules (CD80/86)

Question 22

B lymphocytes

Answer 22

Always express low levels of MHC class II molecules; BCR catches antigen to be presented by B cell
activation occurs after interaction with pathogens via BCR and cytokine signalling, leading to MHC class II expression

Question 23

Nonprofessional APC can exceptionally express MHC class II molecules:

Answer 23

*skin fibroblasts, thymic epithelial cells;
*glial cells, intraepithelial lymphocytes; *pancreatic beta cells, vascular endothelial cells.

Question 24

Human cytomegalovirus, hepatitis B virus, adenovirus 12 interfere with MHC class I molecules

Answer 24

prevent CD8+ T cell activation

Question 25

MHC restriction

Answer 25

refers to the fact that a T cell can interact with a self-major histocompatibility complex molecule and a foreign peptide bound to it, but will only respond to the antigen when it is bound to a particular MHC molecule.

Question 26

CD4+ and CD8+ T cells can

Answer 26

recognize antigen only when it is presented in a groove of an MHC

Question 27

Endogenous antigenes are

Answer 27

processed inside the cells and presented via MHC class I

Question 28

Exogenous antigenes

Answer 28

are taken by endocytosis and presented via MHC class II

Question 29

Peptides are generated by protease complexes called

Answer 29

proteasomes

Question 30

Ubiquitin

Answer 30

proteinsareusedto“tag” intracellular proteins for constitutive proteasome degradation

Question 31

immunoproteasome

Answer 31

cleaves ubiquitinated proteins into fragments that pair better with MHC molecules

Question 32

Antigens enter the APCs by

Answer 32

Phagocytosis (cell eating)
*Endocytosis: specific B-cell receptor mediated * pinocytosis, unspecific cell drinking

Question 33

Endogenous antigens –>

Answer 33

MHC class I –> CD8+ T cells

Question 34

Exogenous antigens –>

Answer 34

MHC class II –> CD4+ T cells

Question 35

not explained mechanistically yet

Answer 35

Influenza virus proteins in pAPCs are associated MHC class II and activate CD4+ T cells
b) autophagy of cytosolic components presented with MHC class II
c) cross presentation- exogenous antigens presented on MHC class I