MHC Flashcards

1
Q

Role of MHC / HLA molecules:
- main role

A

is during Antigen Presentation to T cells

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2
Q
  • play a pivotal role in development of both humoral and cellular immunity
A

MHC/ HLA

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3
Q

MHC/ HLA

  • during transplants:
    used to determine whether a transplanted or to be transplanted tissue is:
A
  • histocompatible and thus accepted
  • recognized as foreign and rejected
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4
Q

MHC/ HLA

  • may be involved during:
A
  • Graft Rejections
  • Autoimmune Diseases
  • Paternity Tests
  • Transfusion Reactions
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5
Q

Why are MHC/ HLA Gene System
- Polymorphic:

A

there are so many possible alleles at each location to increase chances of interacting with diverse self and non-self antigens/immunogens

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6
Q

MHC/ HLA

Coded in the…
Except…

A

short arm of chromosome 6 band 21 (6p21)

Beta-2 in chromosome 15

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7
Q

MHC/ HLA gene system

Divided into 3 categories (classes)

A
  • Class I
  • Class Il
  • Class III
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8
Q

MHC

Class I

A

ABC

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9
Q

MHC CLASS II

A

D:PQR

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10
Q

MHC CLASS III

A

Complement proteins
Cytokines
Tumor necrosis factor

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11
Q

Expressed on cell surface

A

MHC CLASS I and CLASS II

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12
Q

MHC Class I

A

(HLA-A, HLA-B, HLA-C)

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13
Q

MHC Class I

A

(HLA-A, HLA-B, HLA-C)

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14
Q

MHC Class | (HLA-A, HLA-B, HLA-C)

• expressed by…
• highly found on…
• Low or undetectable on… (4)

A

ALL nucleated cells

Lymphocytes & Myeloid Cells

hepatocytes, muscle cells, sperm cells, neural cells

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15
Q

What MHC/ HLA
IS expressed the lowest

A

HLA-C

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16
Q

What MHC/ HLA

(______ and ______ are more important!)

A

HLA-A and HLA-B

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17
Q

Structure of MHC Class I

A

glycoprotein dimer:

2 non-covalently bonded polypeptide chains: - Alpha - Beta

18
Q

Structure of MHC class I

ALPHA chains
- MW: ____
- folded into 3 domains:

-_______ anchored to the cell membrane

A

44,000

  • Alpha 1
  • Alpha 2
  • Alpha 3

polypeptide chain

19
Q

Structure of MHC Class I
BETA chain
- MW:_____
- coded on______
- Beta…
- stabilize folded____
- not polymorphic: why?..

A

12,000

chromosome15

B2 microglobulin

alpha chain

every class I molecule contains the same B2 microglobulin

20
Q

MHC Class III

HLA proteins

A

BF, C2, C4, TNF

21
Q

MHC CLASS I

MHC CLASS II

Chain Structure

A

3 alpha, 1 beta2-microglobulin

2 alpha and 2 beta

22
Q

MHC CLASS I
MHC CLASS II
MHC CLASS III

Found on

A

All nucleated cells

APCS

Blood and other secretions

23
Q

MHC CLASS I
MHC CLASS II

Example of infectious agent

A

Viruses, Tumor, Certain Parasitic Antigens, Intracellular bacteria

Bacteria

24
Q

MHC CLASS I
MHC CLASS II
MHC CLASS III

Antigen Presentation

A

CD8+
CD4+
No role in antigen presentation

25
Q
  • molecular basis for T-cell discrimination of self from non-self
A

Human Leukocyte Antigens

26
Q

HLA

  • Name was given by…
  • discovery of antibody response to…
A

French Scientist (Jean Dausset)

circulating WBCs

27
Q
  • determine whether transplanted tissue is histocompatible and thus accepted or recognized as foreign and rejected
  • Antigen presentation
A

Major Histocompatibility Complex

28
Q
  • in general: Gene system which plays a key immunologic role.
A

MHC

29
Q

Structure of MHC Class I

ALPHA 1 and 2
- serves as…
- able to hold…

A

antigen binding site

8 - 11 amino acids

30
Q

Structure of MHC Class I

ALPHA 3

  • detected by…
A

CD8 on Cytotoxic cells

31
Q

MHC CLASS I NONCLASSICAL GENE

A

EFG

32
Q

Nonclassical antigens

Expression

A

E - cell surface
F - cell surface
G - nit expressed on cell surface

33
Q

Nonclassical antigens

Function

A

E - expressed on fetal trophoblast cells during first trimester of pregnancy protection of placental tissue from NK
cells
F - Unknown
G - expressed on fetal trophoblast cells during first trimester of pregnancy protection of placental tissue from NK
cells

34
Q

MHC Class II (HLA-DP, HLA-DQ, HLA-DR)

•expressed by____

•_______: highest expression

A

APCs

Dendritic cells

35
Q

MHC Class II (HLA-DP, HLA-DQ, HLA-DR)

: lowest

:is expressed at the highest level

A

HLA-DP

HLA-DR

36
Q

MHC Class II (HLA-DP, HLA-DQ, HLA-DR)

is expressed at the highest level accounts for about ½ of Class Il molecules of a particular cell

A

HLA DR

37
Q

MHC Class II (HLA-DP, HLA-DQ, HLA-DR)

: the most highly polymorphic

A

HLA-DR Beta

38
Q

Structure of MHC Class II

  • Consist of…
  • ALPHA
  • BETA
  • _______anchored in the cell membrane
A

two noncovalently bonded polypeptide chains, both of which is encoded at the chromosome 6

Both chains are

39
Q

Structure of MHC Class II

ALPHA chains
- MW:
- folded into 2 domains:

  • both:
A

34,000

  • ALPHA 1
  • ALPHA 2

serves to as recognition sites by T helper cells via the CD4 surface marker

40
Q

Structure of MHC Class II

ALPHA 1 and BETA 1 domains

  • can hold up to…
A
  • antigen-peptide-binding site

13 - 18 aa

41
Q

MHC Class II: Nonclassical
Function
DM
DN
DO

A

Loads peptides onto class Il

Unknown

Modulates antigen binding