antigen processing and presentation histocompatibility

Question 1

MHC

Answer 1

major histocompatibility complex

Question 2

MHC function

Answer 2

-chop up and present antigens to T cells (this can be the cause of rejection or an organ during a transplant)

Question 3

describe MHC genes

Answer 3

polygenic, polymorphic and tend to be codominantly expressed

Question 4

MHC class I

Answer 4

• present peptides to CD8 + T cells
  made up of alpha and beta subunits
• present on all nucleated cells (not Red blood cells)
• displayed on endogenous peptides

Question 5

alpha subunit

Answer 5

large and contains entire peptide binding cleft

Question 6

beta subunit

Answer 6

helps maintain structure of MHC class I

Question 7

MHC Class II

Answer 7

• presents peptides to CD4 +T cells
• expressed on professional antigen presenting cells
• display exogenous peptides
• more symmetrical than class I

Question 8

what are the differences between class I and II peptide binding regions

Answer 8

class I: u shaped curve of 8-10 amino acids, doesn't have to make full contact with the MHC just needs two ends to be anchored on
Class II: binds in a wavy pattern to 13-18 amino acids, almost all amino acids touching MHC

Question 9

antigen processing definition

Answer 9

the breaking down of macromolecules into smaller fragments in order to prepare them for presentation to a t cell

Question 10

one b cell per

Answer 10

one epitope

Question 11

4 major pathways of Ag processing

Answer 11

1. exogenous
2. endogenous
3. cross-presentation
4. autophagic

Question 12

exogenous

Answer 12

internalize antigens and present on cell surface via MHC II. Recognizes external pathogens and only for CD4+T cells

Question 13

endogenous

Answer 13

cell recycling. recognize intracellular pathogens. presented on cell surface of MCH I only presents to CD8+T

Question 14

which cells are best at presenting antigens to T cells because they have high MHCII

Answer 14

dendritic cells

Question 15

which cells can present to either CD4+T and CD8+T

Answer 15

dendritic cells

Question 16

3 types of antigen presenting cells

Answer 16

mature dendritic cells, macrophages and B cells

Question 17

which cells can activate naive t cells

Answer 17

dendritic cells

Question 18

autophagic

Answer 18

recognize internal pathogenic then activate CD4+T cells; present as MCH II

Question 19

cross-presentation

Answer 19

recognize external pathogens and then activate CD8+T cells

Question 20

which cells have highest level of MCH II

Answer 20

dendritic cells

Question 21

Naive t cell activation

Answer 21

by dendritic cells. clonal expansion and differentiation into effector T cells

Question 22

effector t cell activation

Answer 22

can be done by macrophages and b cells. (b cells in the blood and strictly for extracellular pathogens)

Question 23

cells put out to look for antigens

Answer 23

dendritic cells

Question 24

tissue resident resting dendritic cells function

Answer 24

antigen capture

Question 25

activate dendritic cell function

Answer 25

antigen presentation to t cells

Question 26

no ____ peptides go into MHCII

Answer 26

self binding

Question 27

invariant chain

Answer 27

important for exogenous pathway. blocks binding to MHC class II molecules in the ER

Question 28

steps to exogenous pathway

Answer 28

1. substance ingest by APC into endosome. and antigen is degraded via lysosome enzymes 2. MHC II molecules are assembled in ER, Golgi, endosome. Invariant chain keeps alpha and beta chains stable and prevents self Ag binding. 3. MHC II and peptide travel via endosome to cell surface to present Ag to CD 4 cell

Question 29

CLIP

Answer 29

molecule left behind after lysozyme enzymes break down invariant change.

Question 30

HLA-DM

Answer 30

helps to remove CLIP so Ag can bind

Question 31

endogenous pathway steps

Answer 31

1. internal proteins are degraded via the proteasome then transported to ER via TAP 2. MHC I is synthesized and loaded in the ER 3. MHCI/Ag transported to golgi, then the plasma membrane to present to a CD8 T cell

Question 32

TAP

Answer 32

transports internal proteins to the ER during endogenous pathway

Question 33

cross presentation steps

Answer 33

1. APC ingests and processes virally infected cell. (exogenous) 2. Viral proteins enter the cytosol and is processed via endogenous pathway to activate a CD8T cell via MHCI

Question 34

two classes of T-cell receptors

Answer 34

alpha and beta chains (90% of T cells) an γδ (10%)

Question 35

alpha and beta t cells function and location

Answer 35

recognize MHC.AG and reside in secondary lymph tissue

Question 36

γδ t cells function and location

Answer 36

recognizes processed and unprocessed ligands. found in intraepithelial tissue

Question 37

b receptors vs t receptors

Answer 37

b: y shaped t: linear

Question 38

CD8 is a _____ t cell while CD4 is a ____ t cell

Answer 38

cytotoxic, helper

Question 39

TCR cells undergo what type of recombination

Answer 39

VDJ recombination

Question 40

when t cell receptors undergo ____ recombination it creates greater genetic diversity for T cells

Answer 40

variable region recombination

Question 41

4 ways t cell development is similar to b cell development

Answer 41

1. begins in the bone marrow 2. VDJ recombination of variable region of TCR leads to antigen diversity 3. at one point cells express both CD4 and CD8 (double positive) 4. undergo positive and negative selection

Question 42

4 ways t cell development is different from b cell development

Answer 42

1. begins with NK/T precursor cells 2. after leaving the bone marrow thymocytes move to the thymus to finish development 3. MHC molecules are involved in the establishment of central tolerance 4. No possibilities for somatic hypermutation (only undergo positive or negative selection once)

Question 43

CD44

Answer 43

cell adhesion molecule for t cell development

Question 44

CD25

Answer 44

Il-2 receptor for t cell development

Question 45

where must a t cell be to become fully mature

Answer 45

thymus

Question 46

there are 2 times as many ____ t cells in the body

Answer 46

CD4+

Question 47

single positive t cels

Answer 47

the cell has gone through distinction and now it can leave and go to the periphery lymph tissue

Question 48

3 types of t lymphocytes periphery

Answer 48

CD8+-killers CD4+-helpers Treg- suppressors

Question 49

3 signals when a cell meets an antigen presenting cell

Answer 49

1. Ag recognition 2. costimulation 3. cytokines

Question 50

what is needed for survival, proliferation and differentiation of t cells

Answer 50

IL-2

Question 51

during differentiation t cell can become

Answer 51

an effector cell or a memory cell

Question 52

IFNy t cell function

Answer 52

t help for Tc responses against intracellular pathogens Th1.

Question 53

IL-4 function

Answer 53

T help for B cell response against extracellular pathogens Th2

Question 54

IL-17 function

Answer 54

combats infection of skin and mucosae. autoinflamtiaon Th17

Question 55

IL-10 function

Answer 55

peripheral tolerance. iTreg

Question 56

Th1 effector function

Answer 56

classical macrophage activation

Question 57

Th2 effector function

Answer 57

humoral activation of antibodies for extracellular pathogens.

Question 58

Th17 effector functions

Answer 58

inflammation and recruiting neutrophils for barrier functions

Question 59

why do cytotoxic t lymphocytes make many contacts with their targets

Answer 59

to exert effector functions