Lecture 6: The Major Histocompatibility Complex Flashcards

1
Q

What is the MHC?

A

set of closely linked genetic loci that are important in determining fate of engrafted tissue

also play central role in control of cellular interactions for physiological immune responsiveness

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2
Q

What is the function of MHC gene products?

A

to present peptides to T lymphocytes (they constantly sample environment)

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3
Q

What are the 3 Class I HLAs in humans?

A

HLA-A, B, C (cell surface glycoproteins on all nucleated cells that regulate immune cell interactions)

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4
Q

HLA molcules present antigen to ______ T lymphocytes

A

CD8+

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5
Q

What are the Class II HLA Loci?

A

HLA-D

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6
Q

Where are Class II molecules found in the body?

A

on APCs (dendritic cells, B cells, macrophages)

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7
Q

Where in the genome is the MHC found?

A

short arm of chromosome 6

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8
Q

What does the conformation of the Class I MHC molecule look like?

A

one alpha chain (Class I polypeptide) and one light chain B2 microglobulin

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9
Q

True or False: the B2 microglobulin is the same in all MHC class I molecules

A

True (the alpha chains differ)

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10
Q

Peptide binding cleft of MHC Class I is made of ___ and ____.

A

alpha 1 and alpha 2

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11
Q

the cytoplasmic tail of MHC Class I is made of ___

A

alpha 3 (traverses the cell membrane)

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12
Q

In terms of peptide length, MHC Class I binds _________ peptides and MHC Class II binds __________ peptides

A

short; longer

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13
Q

What does the peptide binding cleft look like for MHC Class II?

A

one beta 1 and one alpha 1

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14
Q

True or false: B2 microglobulin is encoded within the MHC region of chromosome 6

A

FALSE

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15
Q

What is the pattern of MHC antigen expression?

A

CO-DOMINANT (in other words, all 3 maternal and 3 paternal class I molecular types as well as Class II types are expressed)

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16
Q

Each individual has 2 half sets of MHC genes making them what?

A

haplotypes

17
Q

What is the benefit of polymorphism in MHC?

A

can present wider diversity of environmental antigens

18
Q

What is MHC Restriction?

A

dependence of T cells specific reactivity on foreign Ag plus MHC products rather than on foreign Ag alone.