MHC Ag Flashcards

1
Q

Importance of the Major Histocompatibility Complex

A
  1. CD4 and CD8 activation T cell activation
  2. B cell activation
  3. Disease susceptibility
  4. vaccine development strategies
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2
Q

Professional antigen presenting cells

A

macrophages and B cells

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3
Q

Exogenous Pathway

A

antigen comes from outside the cell.

  1. antigen is presented to CD4+ (helper) T cells
  2. This presentation required MHCII molecules
  3. Contributes to CD4+ responses (activation)
  4. expands CD4+ effector cells
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4
Q

Which cells express MHC II

A

dendritic cells, B cells, macrophages

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5
Q

Steps of Antigen Processing with MHC II

A
  1. antigen capture and uptake
  2. internalized antigen degraded
  3. generation of MHC II/peptide complexes
  4. transport of MHC II/peptide complexes to cell surface
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6
Q

Steps of Antigen Processing by B cells

A
  1. antigen capture and uptake by B cell receptor
  2. internalized antigen degraded by endocytosis- membrane pinched off, neutral pH, antigen is processed by catalytic enzymes
  3. MHC II are generated in endoplasmic reticulum. Peptides become associated with MHC II
  4. Peptides displayed on cell surface in the MHC II
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7
Q

What is required for efficient antigen capture by B cells?

A

high affinity antibody

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8
Q

Steps of Antigen processing by macrophages

A
  1. phagocytosis of microorganisms
  2. phagocytic vesicle fuses with an intracellular lysosome forming phagolysosome, pH >5
  3. MHC II are generated in endoplasmic reticulum. Peptides become associated with MHC II
  4. Peptides displayed on cell surface in the MHC II
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9
Q

Non-professional antigen presenting cells

A

epithelial, endothelial, stromal. Interferon gamma can induce MHC II

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10
Q

Goal of MHC II

A

activation of T helper cellsq

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11
Q

Endogenous Pathway

A

MHC I- peptide produced inside cell

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12
Q

MHC I Pathway

A

goal is to stimulate cytotoxic T cells to destroy altered or infected cells. MHC I molecules are present on almost all nucleated cells

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13
Q

Steps of MHC I Pathway

A
  1. endogenous antigen produced in cell
  2. antigen tagged by ubiquitin
  3. antigen enters proteasome
  4. antigen degraded into peptide fragments 8-10AA
  5. peptide released into cytosol
  6. migrate to ER via TAP-1 and TAP-2
  7. moves to ER
  8. MHC I binds peptide
  9. moves to golgi
  10. peptide antigen displayed on cell surface with MHC I
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14
Q

What does captured antigen become?

A

it is cleaved by proteases into peptides

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15
Q

Cell stimulated in MHC I

A

CD8 cytotoxic T cell

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16
Q

Cell stimulated in MHC II

A

CD4 helper T cell

17
Q

Peptide displayed in MHC I

A

8-10 amino acids

18
Q

Peptide displayed in MHC II

A

13-18 amino acids

19
Q

Antigen recognition in MHC I

A

tagged by ubiquitin

20
Q

Antigen recognition in MHC II

A

receptor mediated

21
Q

Location of MHC I

A

all nucleated cells

22
Q

Location of MHC II

A

antigen presenting cells

23
Q

Source of antigen in MHC I

A

endogenous

24
Q

Source of antigen in MHC II

A

exogenous

25
Q

Binding domains in MHC I

A

alpha 1, alpha 2

26
Q

Binding domains in MHC II

A

alpha 1, beta 1

27
Q

MHC

A

major histocompatibility complex

28
Q

Cross Presentation

A

antigens are brought into the APC by mechanisms normally leading to presentation with MHC II. Antigen is presented on an MHC I molecule for CD8 T cells. Exact mechanism no yet well understood. Primarily a function of dendritic cells and not macrophages or B cells

29
Q

What types of antigens are not processed well via the endogenous pathway?

A

carbohydrates, nucleic acids, lipids

30
Q

How would killed bacterial vaccine antigens be processed?

A

MHC II pathway

31
Q

How would live attenuated vaccine antigens be processed?

A

both MHC I and MHC II pathways

32
Q

How would mRNA vaccine antigens be processed

A

both MHC I and MHC II pathway

33
Q

How would replication defective virus vectored DNA vaccine antigens be processed?

A

both MHC I and MHC II pathway

34
Q

MHC class III Gene Products

A

complement (C4, FB, C2), TNF alpha, NK cell receptors, heat shock protein

35
Q

What do MHC II molecules present?

A

processed foreign antigens from phagolysosomes

36
Q

What type of antigen-presenting molecule is found on all nucleated cells?

A

MHC I

37
Q

Which type of antigen-presenting molecule is found only on macrophages, dendritic cells, and B cells?

A

MHC II

38
Q

MHC II molecules are made of two subunits of approximately equal size, whereas MHC I molecules consist of a larger alpha subunit and a smaller subunit called:

A

beta 2 microglobulin

39
Q

What does MHC I and MHC II diversity do?

A

affect the fitness of individuals with regard to fighting certain diseases