Major Histocompatibility Complexes Flashcards

0
Q

MHC is a…

A

genetic complex

in ALL vertebrate species

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1
Q

MHC stands for

A

Major Histocompatibility Complex

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2
Q

MHC genes are….

A

polymorphic (come in MANY genetic forms)

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3
Q

Classes of MHC

A

MHC Class I

MHC Class II

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4
Q

MHC I Structure

A

PART PRESENTED TO T-CELLS:
alpha-1 bind to membrane. alpha-2 & -3 combined form peptide-binding cleft. B-2 microglobulin doesn’t contribute to it’s function.

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5
Q

MHC II Structure

A

PART PRESENTED TO T-CELLS:

B-2 and a-2 bind to cell membrane. b-1 and a-1 form peptide-binding cleft.

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6
Q

MHC I expressed by

A

ALL nucleated cells

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7
Q

MHC I present Ag to…

A

CD8 T-cells

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8
Q

MHC I presents Ags that are…

A

sythesized inside the cell

cytosolic pathogens

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9
Q

Types of Ags presented by MHC I

A

viral antigens

intracellular parasites

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10
Q

MHC II expressed by…

A

dendritic cells
macrophages
B-cells

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11
Q

MHC II present Ags to…

A

CD4 T-cells

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12
Q

MHC II presents Ags that are…

A

made outside the cell and internalized

intravesicular pathogens & extracellular pathogens & toxins

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13
Q

Types of Ags presented by MHC II

A

extracellular parasites

extracellular phase of intracellular parasites

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14
Q

MHC functions

A

transport intracellular antigens to the surface of a cell where the TCR can “see” it

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15
Q

MHC I Antigen Processing

A

Tumer antigen coding region in nueclues –> endogenously synthesized Ag –> proteasome –> peptides –> peptide enters ER & binds to MHC I –> MHC I + Ag go to Golgi then DGN –> cell membrane

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16
Q

MHC II Antigen Processing

A

endocytosis of protein antigen –> Ag endosome joins MHC II containing endosome –> Ag binds to MHC II –> MHC II on plasma membrane

17
Q

Peptide-Binding Selectivity of MHC I and II

A

MHC I and II bind to many different peptides but have preferences for certain amino acids that must be present to bind.
the requirements for binding aren’t as strict as Ag:Ab binding.

SELECTIVE rather than SPECIFIC binding

18
Q

What happens when MHC is less polymorphic?

limited polymorphism

A

a more limited number of antigenic peptides that can be present to T-cells.

19
Q

examples of diseases related to limited polymorphism

A
  1. Feline infectious peritonitis in Cheetahs

2. Tasmanian devil facial tumors that are “transplanted” from biting (they don’t make MHC)

20
Q

MHC alleles associated with susceptility & sometimes resistance to…

A

mostly autoimmune diseases

21
Q

MHC polymorphism means…

A

each groove on the various MHC molecules is different from the others, making it highly specific to TCRs

22
Q

Canine Disease Associations with MHC alleles

A

probably due to the way Ags are presented by the MHC which leads to an increased risk of disease.

23
Q

Infectious Disease Resistance/Susceptibility

A
  • has potential associations with MHC alleles
  • probably because viruses have lots of antigenic peptides and at least one of them will bind to MHC and be presented. THEREFORE, the diseases aren’t as effective.
24
Q

Cytosolic pathogen peptides bind to…

A

MHC I

25
Q

Intravesicular pathogens bind to

A

MHC II

26
Q

Extracellular pathogens & toxins bind to…

A

MHC II

27
Q

cytosolic pathogens are presented to…

A

effector CD8 T-cells (cytotoxic T-cells)

28
Q

intravesicular pathogens are presented to…

A

Effector CD4 T-cells (helper T-cells)

29
Q

extracellular pathogens & toxin are presented to…

A

effector CD4 T-cells (helper T-cells)

30
Q

When cytosolic pathogens are presented to T-cells, the cell they’re on….

A

dies!

31
Q

When intravesicular pathogens are presented to CD4 t-cells, the cell they’re on is…

A

activated to kill intravesicular bacteria & parasites

32
Q

When extracellular pathogens & toxins are presented to CD4 T-cells, the cell they’re on…

A

gets activated to secrete Abs to eliminate extracellular bacteria/toxins

33
Q

Type of cell cytosolic pathogens are presented on

A

any nucleated cell

34
Q

Type of cell intravesicular pathogens are presented on…

A

macrophages

35
Q

Type of cell extracellular pathogens & toxins are presented on…

A

B-cells

36
Q

Cytosolic pathogens are degraded in…

A

cytosol

37
Q

Intravesicular pathogens are degraded in..

A

endocytic vesicles (low pH)

38
Q

Extracellular pathogens & toxins are degraded in…

A

Endocytic vesicles (low pH)

39
Q

Effector CD4 T-cells are presented…

A

intravesicular pathogens and extracellular pathogens & toxins via MHC II

40
Q

Effector CD8 T-cells are presented….

A

cytosolic pathogens via MHC I