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Microbiology > antigen processing and presentation histocompatibility > Flashcards

antigen processing and presentation histocompatibility Flashcards

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1
Q

MHC

A

major histocompatibility complex

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2
Q

MHC function

A

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

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3
Q

describe MHC genes

A

polygenic, polymorphic and tend to be codominantly expressed

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4
Q

MHC class I

A
  • 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
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5
Q

alpha subunit

A

large and contains entire peptide binding cleft

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6
Q

beta subunit

A

helps maintain structure of MHC class I

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7
Q

MHC Class II

A
  • presents peptides to CD4 +T cells
  • expressed on professional antigen presenting cells
  • display exogenous peptides
  • more symmetrical than class I
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8
Q

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

A 
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
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9
Q

antigen processing definition

A

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

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10
Q

one b cell per

A

one epitope

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11
Q

4 major pathways of Ag processing

A
  1. exogenous
  2. endogenous
  3. cross-presentation
  4. autophagic
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12
Q

exogenous

A

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

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13
Q

endogenous

A

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

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14
Q

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

A

dendritic cells

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15
Q

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

A

dendritic cells

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16
Q

3 types of antigen presenting cells

A

mature dendritic cells, macrophages and B cells

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17
Q

which cells can activate naive t cells

A

dendritic cells

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18
Q

autophagic

A

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

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19
Q

cross-presentation

A

recognize external pathogens and then activate CD8+T cells

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20
Q

which cells have highest level of MCH II

A

dendritic cells

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21
Q

Naive t cell activation

A

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

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22
Q

effector t cell activation

A

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

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23
Q

cells put out to look for antigens

A

dendritic cells

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24
Q

tissue resident resting dendritic cells function

A

antigen capture

25
Q

activate dendritic cell function

A

antigen presentation to t cells

26
Q

no ____ peptides go into MHCII

A

self binding

27
Q

invariant chain

A

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

28
Q

steps to exogenous pathway

A
  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
29
Q

CLIP

A

molecule left behind after lysozyme enzymes break down invariant change.

30
Q

HLA-DM

A

helps to remove CLIP so Ag can bind

31
Q

endogenous pathway steps

A
  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
32
Q

TAP

A

transports internal proteins to the ER during endogenous pathway

33
Q

cross presentation steps

A
  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
34
Q

two classes of T-cell receptors

A

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

35
Q

alpha and beta t cells function and location

A

recognize MHC.AG and reside in secondary lymph tissue

36
Q

γδ t cells function and location

A

recognizes processed and unprocessed ligands. found in intraepithelial tissue

37
Q

b receptors vs t receptors

A

b: y shaped
t: linear

38
Q

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

A

cytotoxic, helper

39
Q

TCR cells undergo what type of recombination

A

VDJ recombination

40
Q

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

A

variable region recombination

41
Q

4 ways t cell development is similar to b cell development

A
  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
42
Q

4 ways t cell development is different from b cell development

A
  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)
43
Q

CD44

A

cell adhesion molecule for t cell development

44
Q

CD25

A

Il-2 receptor for t cell development

45
Q

where must a t cell be to become fully mature

A

thymus

46
Q

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

A

CD4+

47
Q

single positive t cels

A

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

48
Q

3 types of t lymphocytes periphery

A

CD8+-killers
CD4+-helpers
Treg- suppressors

49
Q

3 signals when a cell meets an antigen presenting cell

A
  1. Ag recognition
  2. costimulation
  3. cytokines
50
Q

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

A

IL-2

51
Q

during differentiation t cell can become

A

an effector cell or a memory cell

52
Q

IFNy t cell function

A

t help for Tc responses against intracellular pathogens Th1.

53
Q

IL-4 function

A

T help for B cell response against extracellular pathogens Th2

54
Q

IL-17 function

A

combats infection of skin and mucosae. autoinflamtiaon Th17

55
Q

IL-10 function

A

peripheral tolerance. iTreg

56
Q

Th1 effector function

A

classical macrophage activation

57
Q

Th2 effector function

A

humoral activation of antibodies for extracellular pathogens.

58
Q

Th17 effector functions

A

inflammation and recruiting neutrophils for barrier functions

59
Q

why do cytotoxic t lymphocytes make many contacts with their targets

A

to exert effector functions

Microbiology (7 decks)

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