Page 531 - Review of Medical Microbiology and Immunology ( PDFDrive )

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PART VII Immunology
520
double-stranded RNA). These interferons exert a pow-
(C) Th-2 cells synthesize gamma interferon, which is important in
erful antiviral activity by inducing the synthesis of a
controlling infections caused by Staphylococcus aureus and
other pyogenic bacteria.
ribonuclease that degrades viral mRNA, thereby inhib-
(D) Th-1 cells are involved with delayed hypersensitivity reactions,
iting viral replication. They also activate NK cells,
such as those that control infections caused by M. tuberculosis.
causing those cells to kill virus-infected cells more
effectively. (See Chapter 33.)
of T cells, which one of the following is the most accurate?
Gamma interferon is a lymphokine produced primarily
by the Th-1 subset of helper T cells and is the “signature”
are deleted, a process known as negative selection.
cytokine involved in the inflammation mediated by those (A) T cells bearing antigen receptors that recognize self antigens
(B) Superantigens are “super” because they play a selective role in
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cells (Table 58–5). It is one of the most potent activators of
both the positive and the negative selection that occurs in the
the phagocytic activity of macrophages, NK cells, and neu-
thymus.
trophils, thereby enhancing their ability to kill microorgan-
(C) T cells bearing antigen receptors that recognize antigen in asso-
isms and tumor cells. It does so by inducing the synthesis
ciation with foreign MHC proteins survive, a process known as
of NADPH oxidase which produces reactive oxygen species
positive selection.
that are highly microbicidal. For example, it greatly
(D) Most mature T cells have both CD4 and CD8 proteins in their
surface that ensures their ability to react with antigen presented
increases the killing of intracellular bacteria, such as M.
by either MHC class I or MHC class II proteins.
tuberculosis, by macrophages. It also increases the synthesis
of class I and II MHC proteins in a variety of cell types. This
accurate?
enhances antigen presentation by these cells.
(2) Lymphotoxin (also known as TNF-β) is made by
to IgG.
activated T lymphocytes and causes effects similar to those
(B) IL-4 is made by cytotoxic T cells and mediates the killing of
of TNF-α. It binds to the same receptor as TNF-α and (A) IL-2 is made by B cells and increases class switching from IgM
virus-infected cells.
hence has the same effects as TNF-α.
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(C) IL-12 is made by eosinophils and enhances the production of
cells that mediate immediate hypersensitivity.
SELF-ASSESSMENT QUESTIONS
(D) Gamma interferon is made by Th-1 cells and activates macro-
phages to phagocytose more effectively.
1. One of the cells involved in certain autoimmune diseases is described
as a CD3-positive, CD4-positive cell. Regarding this cell, which one
accurate?
of the following is the most accurate regarding its function?
(A) Chemokines penetrate the membranes of target cells during
(A) Produces IgA
attack by cytotoxic T cells.
(B) Produces interleukin-2
(B) Chemokines bind to the T-cell receptor outside of the antigen-
(C) Kills virus-infected cells
binding site and activate many T cells.
(D) Presents antigen in association with class II MHC proteins
(C) Chemokines attract neutrophils to the site of bacterial infec-
(E) Recognizes antigen in association with class I MHC proteins
tion, thereby playing a role in the inflammatory response.
2. Which one of the following sets of cells can present antigen to
(D) Chemokines induce gene switching in B cells, which increases
helper T cells?
the amount of IgE synthesized, thereby predisposing to
(A) B cells and dendritic cells
allergies.
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(B) B cells and cytotoxic T cells
(C) Macrophages and eosinophils
den onset of fever, vomiting, myalgias, and diarrhea. This was fol-
(D) Neutrophils and cytotoxic T cells
lowed by hypotension and a sunburn-like rash over most of her
(E) Neutrophils and plasma cells
body. You make a presumptive diagnosis of toxic shock syndrome.
3. The activation of a CD8-positive T lymphocyte requires presenta-
Which one of the following is the most accurate description of the
tion of antigen in association with which one of the following?
pathogenesis of this disease?
(A) Class I MHC protein and synthesis of interleukin-2 by CD4 T
(A) It is caused by the release of large amounts of histamine from
lymphocytes
basophils.
(B) Class I MHC protein and synthesis of gamma-interferon by
(B) It is caused by an insufficient amount of inhibitor of the C1
macrophages
component of complement.
(C) Class II MHC protein and synthesis of interleukin-1 by
macrophages
of cytokines from helper T cells.
(D) Class II MHC protein and synthesis of interleukin-4 by CD4 T
(D) It is caused by a delayed hypersensitivity response to procain-
lymphocytes (C) It is caused by a superantigen that induces an overproduction
amide, which she was taking for her atrial fibrillation.
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4. Regarding Th-1, Th-2, and Th-17 cells, which one of the following
(E) It is caused by a mutation in the gene for ZAP-70, one of the
is the most accurate?
signal transduction proteins in T lymphocytes.
(A) Th-17 cells produce interleukin-17, which stimulates the pro-
duction of Th-2 cells.
(B) The production of Th-1 cells is enhanced by interleukin-4,
whereas the production of Th-2 cells is enhanced by
interleukin-2.
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