Deck 16: Antigen-Processing

Question 1

A child who suffers from a persistent viral infection is found to have a deficiency in lymphocyte production and very few T and B cells.Other bone marrow-derived cells are produced in normal numbers,and MHC molecule expression on cells appears normal.Transfusion of mature T cells from an unrelated donor who had recovered from a previous infection by the same virus would not be expected to help the child clear his infection.Which one of the following is a reasonable explanation for why this therapeutic approach would fail?

A)Viral infections are cleared by antibodies,not T cells.
B)The patient's own immune system would destroy the transfused T cells before they could respond to the viral infection.
C)T cells recognize peptides,not viral particles.
D)Donor T cell viral antigen recognition is restricted by MHC molecules not expressed in the patient.
E)In responding to the previous infection,the donor would have used up all his T cells specific for that virus.

Answer 1

Donor T cell viral antigen recognition is restricted by MHC molecules not expressed in the patient.

Question 2

Match the description in questions with the lettered item (A-I)related to antigen-presentation pathways.
Site of peptide loading of class I MHC molecules

A)T cell receptor on CD4+ T cells
B)Endosomes
C)Endoplasmic reticulum
D)Invariant chain
E)Class II-associated invariant chain peptide (CLIP)
F)LMP-2 and LMP-7
G)Acidic proteases
H)T cell receptor on CD8+ T cells
I)HLA-DM

Answer 2

Endoplasmic reticulum

Question 3

Many vaccines now include highly purified,recombinant,or synthetic peptide antigens.Given alone,the antigens in these vaccines would be less immunogenic than vaccines containing intact killed or live microbes.Adjuvants are substances added to purified protein or peptide vaccines to enhance their ability to elicit T cell immune responses.Which of the following statements about these adjuvants is NOT correct?

A)They induce local inflammation,thereby increasing the number of antigen-presenting cells (APCs)at the site of immunization.
B)They stimulate the expression of costimulators on local APCs.
C)They enhance local production of cytokines that promote T cell activation.
D)They prolong the expression of peptide-MHC complexes on the surface of APCs.
E)They bind to T cell antigen receptors and promote their proliferation.

Answer 3

They bind to T cell antigen receptors and promote their proliferation.

Question 4

A helper T cell response to a protein antigen requires the participation of antigen-presenting cells that express which of the following types of molecules?

A)Class II MHC and costimulators
B)Class I MHC and CD4
C)Class II MHC and CD8
D)CD4 and costimulators
E)Class II MHC and CD4

Question 5

Match the description in questions with the lettered item (A-I)related to antigen-presentation pathways.
The molecule that binds to the final product of the class II antigen-pocessing pathway

A)T cell receptor on CD4+ T cells
B)Endosomes
C)Endoplasmic reticulum
D)Invariant chain
E)Class II-associated invariant chain peptide (CLIP)
F)LMP-2 and LMP-7
G)Acidic proteases
H)T cell receptor on CD8+ T cells
I)HLA-DM

Question 6

Match the description in questions with the lettered item (A-I)related to antigen-presentation pathways.
A protein that binds to newly synthesized class II MHC molecules in the endoplasmic reticulum (ER),which blocks the peptide binding site and directs transport of the class II MHC molecule to endosomes.

A)T cell receptor on CD4+ T cells
B)Endosomes
C)Endoplasmic reticulum
D)Invariant chain
E)Class II-associated invariant chain peptide (CLIP)
F)LMP-2 and LMP-7
G)Acidic proteases
H)T cell receptor on CD8+ T cells
I)HLA-DM

Question 7

Match the description in questions with the lettered item (A-I)related to antigen-presentation pathways.
Required for proteolytic generation of class I MHC-binding peptides

A)T cell receptor on CD4+ T cells
B)Endosomes
C)Endoplasmic reticulum
D)Invariant chain
E)Class II-associated invariant chain peptide (CLIP)
F)LMP-2 and LMP-7
G)Acidic proteases
H)T cell receptor on CD8+ T cells
I)HLA-DM

Question 8

Antigen-presenting cells (APCs)perform which of the following functions in adaptive immune responses?

A)Display major histocompatibility complex (MHC)-associated peptides on their cell surfaces for surveillance by B lymphocytes
B)Initiate T cell responses by specifically recognizing and responding to foreign protein antigens
C)Display MHC-associated peptides on their cell surfaces for surveillance by T lymphocytes
D)Display polysaccharide antigens on their cell surfaces for surveillance by B lymphocytes
E)Secrete peptides derived from protein antigens for binding to T cell antigen receptors

Question 9

Match the description in questions with the lettered item (A-I)related to antigen-presentation pathways.
Site of proteolysis of antigens in the class II MHC pathway

A)T cell receptor on CD4+ T cells
B)Endosomes
C)Endoplasmic reticulum
D)Invariant chain
E)Class II-associated invariant chain peptide (CLIP)
F)LMP-2 and LMP-7
G)Acidic proteases
H)T cell receptor on CD8+ T cells
I)HLA-DM

Question 10

The cell type shown below is found between follicles in lymph nodes and expresses B7-1,B7-2,and class II MHC.What type of cell is this?

A)B cell
B)Follicular dendritic cell
C)Thymic epithelial cell
D)Dendritic cell
E)Plasma cell