Page 71 - Review of Medical Microbiology and Immunology ( PDFDrive )
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PART I Basic Bacteriology
60
IgG is the main opsonizing antibody, IgG and IgM activate
complement, and IgA interferes with attachment to the
• Reduced host defenses result in an increase in the frequency
mucosa.
and severity of infections. The main causes include various
• The main functions of cell-mediated immunity are to protect
genetic immunodeficiencies, the presence of foreign bodies,
against intracellular bacteria and to kill virus-infected cells.
and the presence of certain chronic diseases, such as diabetes
Helper T cells (and macrophages) protect against intracellular
mellitus and renal failure.
bacteria, whereas cytotoxic T cells kill virus-infected cells.
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SELF-ASSESSMENT QUESTIONS
(A) bacteria are made more easily phagocytized.
1. Which one of the following host defense processes is the MOST
(B) chemokines attract neutrophils to the site of infection.
important in preventing the action of exotoxins?
(C) neutrophils migrate from the blood through the endothelium
(A) Binding of cytokines to exotoxin-specific receptors inhibits the
to reach the site of infection.
attachment of exotoxins.
(D) the acute-phase response is induced.
(B) Degradation of exotoxins by the membrane attack complex of
(E) the alternate pathway of complement is activated.
complement.
(C) Lysis of exotoxins by perforins produced by cytotoxic T cells.
(D) Neutralization of exotoxins by antibody prevents binding to
target cell membrane.
1. (D)
(E) Phagocytosis of exotoxins by neutrophils and subsequent ANSWERS
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(A) Gamma interferon receptor mebooksfree.com
2. (C)
destruction by hypochlorite.
3. (D)
2. An inflammatory response in the skin is characterized by ery-
4. (A)
thema (redness). Which one of the following is the most impor-
tant cause of this erythema?
(A) C3b component of complement
PRACTICE QUESTIONS: USMLE &
(B) Gamma interferon
COURSE EXAMINATIONS
(C) Histamine
(D) Hypochlorite
Questions on the topics discussed in this chapter can be found
(E) Superoxide
in the Basic Bacteriology section of Part XIII: USMLE (National
3. A 1-year-old child with repeated infections was diagnosed with
chronic granulomatous disease (CGD). A defect in which one of
USMLE (National Board) Practice Examination starting on
the following is the cause of CGD?
(B) LFA-integrins Board) Practice Questions starting on page 709. Also see Part XIV:
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(C) Mannose-binding protein
(D) NADPH oxidase
(E) Nitric oxide
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