U E S T I O N S

7. Describe an Arthus reaction.

8. Why might malnutrition lead to immunodeficiencies?

9. What is the most common primary immunodeficiency disorder?

10. How can genetic abnormalities leading to immunodeficiency disorders be corrected? Give an example.

Multiple Choice

1. An IgE-mediated allergic reaction

A. reaches a peak within minutes after exposure to antigen.

B. occurs only to polysaccharide antigens.

C. requires complement activation.

D. requires considerable macrophage participation.

E. is characterized by induration.

458 Chapter 18 Immunologic Disorders

2. Which of the following statements is true of the ABO blood group system in humans?

A. A antigen is present on type O red cells.

B. B antigen is the most common antigen in the population of the United States.

C. Natural anti-A and anti-B antibodies are of the class IgG.

D. People with blood group O do not have natural antibodies against A and B antigens.

E. In blood transfusions, incompatibilities cause complement lysis of red blood cells.

3. All of the following are true of immune complexes, except

A. the most common complexes consist of antigen-IgE-complement.

B. an immune complex consists of antigen attached to antibody.

C. usually complement components are included in antigen-antibody complexes.

D. immune complexes activate strong inflammatory reactions.

E. immune complexes deposit in kidneys, joints, and skin.

4. Delayed hypersensitivity reactions in the skin

A. are characterized by a wheal and flare reaction.

B. peak at 4 to 6 hours after exposure to antigen.

C. require complement activation.

D. show induration because of the influx of sensitized T cells and macrophages.

E. depend on activities of the Fc portion of antibodies.

5. Organ transplants, such as of kidneys

A. are experimental at present.

B. can be successful only if there are exact matches between donor and recipient.

C. survive best if radiation is used for immunosuppression.

D. survive best if B cells are suppressed.

E. are rejected by a complex process in which cellular mechanisms predominate.

6. All of the following are true of autoimmune diseases, except

A. many of them show association with particular major histocompatibility types.

B. some of them often occur in members of the same family.

C. during heart attacks heart antigens are released, but no response occurs to them.

D. disease may result from reaction to viral antigens that are similar to antigens of self.

E. some are organ-specific and some are widespread in the body.

7. Autoantibody-induced autoimmune diseases

A. can sometimes be passively transferred from mother to fetus.

B. include diabetes mellitus.

C. are always organ-specific.

D. are never organ-specific.

E. cannot be treated.

8. All of the following are approaches being used to treat autoimmune diseases, except

A. cytotoxic drugs to prevent lymphoid cell proliferation.

B. cyclosporin.

C. antibiotics.

D. steroid with anti-inflammatory action.

E. replacement therapy, as with insulin in diabetes.

9. Patients with primary immunodeficiencies in the complement system

A. who lack late-acting components (C5, C6, C7, C8) show increased susceptibility to Neisseria infections.

B. who lack C3 are prone to develop tuberculosis.

C. generally have no symptoms.

D. only show defects in the major components, C1 through C9.

E. usually handle infections normally.

10. One of the most serious of the secondary immunodeficiencies is

A. acquired immunodeficiency syndrome, caused by the human immunodeficiency virus.

B. severe combined immunodeficiency.

C. DiGeorge syndrome.

D. chronic granulomatous disease.

E. Chediak-Higashi disease.

Applications

1. Patients with advanced leprosy do not give positive type IV reactions to any of a variety of antigens that normal people are exposed to and usually respond to with a positive delayed hypersensitivity skin reaction. Why might this be? What is another disease where lack of the ability to give a positive delayed hypersensitivity reaction could be a useful diagnostic criterion?

2. The BCG vaccine against tuberculosis is not very effective, and great efforts are being made to produce a better vaccine. Nevertheless, BCG vaccine does give some protection and it is routinely used in many countries of the world, but not the United States. Since tuberculosis is far from eradicated in the United States, why would the BCG vaccine not be used?

Critical Thinking

1. Hypersensitivity reactions, by definition, lead to tissue damage. Can they also be beneficial? Explain.

2. Why does blood need to be cross-matched before transfusion? Why not just type the blood and use compatible ABO types?

3. What hypothesis could explain why primary immunodeficiencies are generally rare?

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