Antigen Presentation and the MHC Flashcards

1
Q

What is on the surface of professional antigen presenting cells?

A

Both Class I and Class II MHCs

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2
Q

Of the APCs which one is not phagocytic?

A

B lymphocytes

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3
Q

How do dendritic cells change in function as they mature?

A

Immature DCs are phagocytic, mature ones are not.

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4
Q

What are plasmacytoid dendritic cells?

A

Plasmacytoid dendritic cells produce large quantities of interferon in response to viral infections.

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5
Q

What are conventional dendritic cells?

A

They develop from highly phagocytic cells to mature dendritic cells that present large quantities of peptide in the context of MHC class II molecules.

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6
Q

What is the difference in the antigen presentation of B lymphocytes VS DCs?

A

B lymphocytes present only one kind of antigen via cell surface receptor

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7
Q

Describe antigen processing in Class I MHC.

A

Viral proteins in the cytoplasm are bound by MHC Class I proteins and are transported to the cell surface for antigen presentation.

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8
Q

Describe antigen processing in Class II MHC.

A

Extracellular protein is taken into vesicles into the cell and the vessel is acidified and proteases are active to break them down and MHC Class II vesicles fuse and bind the peptides. It is then exported to the cell membrane.

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9
Q

Describe Class II MHC antigen processing on B lymphocytes.

A

Antigen specific B cell binds its antigen and it is taken in and vesicles of the MHC Class II receptor join it and the antigen is bound and exported to the membrane.

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10
Q

For antigen processing in Class I, what degrades the antigens?

A

Proteasome

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11
Q

Where are the degraded Class I MHC antigens taken to and how?

A

They are transported to the endoplasmic reticulum of the cell by TAP1 and TAP2 transporters.

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12
Q

What are the chaperones that help the MHC Class I proteins fold?

A

Calnexin/Calreticulin/ERp57

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13
Q

What is the function of ERAAP?

A

When peptides are transported into the endplasmic reticulum they are trimmed by ERAAP before binding to the MHC

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14
Q

What do Class I MHCs present under normal conditions?

A

Present normal host peptides

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15
Q

How is the Class II MHC receptor prepared for binding antigens? (Involves invariant chain and CLIP)

A

Within the endosome, acidification cleaves Invariant Chain leaving a short peptide fragment, CLIP. CLIP is removed by HLA-DM and foreign antigen is loaded.

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16
Q

What do Class II MHCs present under normal conditions?

A

CLIP

17
Q

What do CD4 T lymphocytes recognize?

A

They recognize antigen on the surface of APCs in the context of class II molecules.

18
Q

What are Th1 T lymphocytes specific for?

A

Macrophage activation

19
Q

What are Th2 T lymphocytes specific for?

A

Antibody synthesis

20
Q

What does CD4 of T cells bind?

A

Non-polymorphic region of the MHC Class II molecule

21
Q

What are the two signals required for the activation of a naive T cell?

A
  • Presentation of peptides by MHC

- Interaction of the APC’s B7 with the T cell’s CD28

22
Q

How are T cells activated when the APC has taken up a cell that is not a microorganism and thus does not express B7?

A

T cells that recognize peptides expressed by MHC class II on the surface of the APC are stimulated to express CD40L, which binds to the CD40 of the APC.

23
Q

What does CD40-CD40L interaction result in?

A

It activates the T cell to produce cytokines, allowing the B cell to proliferate and differentiate into plasma cells that secrete antibody.

24
Q

What is the function of LFA1 binding ICAM1?

A

LFA-1 binds ICAM-1 to allow for the TCR to sample
the MHC Class II molecule -> if it is not specific for
that MHC II then nothing happen

25
Q

What are CD8 T cells?

A

Cytptoxic T

26
Q

What are CD4 T cells?

A

Helper T