Question 1

A child who is being evaluated for an immune deficiency fails to make antibody to tetanus toxoid or pneumococcal vaccine, but shows normal cell-mediated immunity as indicated by a positive skin test (swelling and redness) to a commonly encountered environmental antigen. This child has an abnormality of which cell lineage?

A)T cells
B)B cells
C)Monocytes/macrophages
D)Dendritic cells

B

Accepted Answer

Failing to produce antibodies to specific vaccines indicates a deficiency in B cells, which are responsible for antibody production. Normal cell-mediated immunity suggests that T cells, monocytes/macrophages, and dendritic cells are functioning normally.

Question 2

Tolerance to one's own body is due to which of the following?&#10;A)Lack of antigens on cells&#10;B)Lack of antigen receptors on lymphocytes&#10;C)Loss of lymphocyte clones reactive to native antigens&#10;D)Activation of suppressor cells

Accepted Answer

Tolerance to one's own body is primarily due to the deletion or inactivation of lymphocyte clones that are reactive to self-antigens during the development of the immune system. This process ensures that the immune system does not attack the body's own tissues.

Question 3

Which of the following statements is correct regarding patients with acquired immunodeficiency syndrome?&#10;A)They will be able to generate a normal antibody response&#10;B)They have normal T helper cells&#10;C)They have an increased secretion of interleukins&#10;D)They have a decrease in CD4+ cells

Accepted Answer

Patients with acquired immunodeficiency syndrome (AIDS) have a decrease in CD4+ T-helper cells, which are essential for immune system function. This leads to an impaired ability to mount a normal antibody response and an increased risk of opportunistic infections. They also have impaired cellular immunity and may have an abnormal secretion of interleukins. Therefore, option D is the correct statement among the given options.

Question 4

In sensitized persons, immediate hypersensitivity responses are primarily the result of liberation of vasoactive substances by the action of which of the following?&#10;A)Activated T lymphocytes on smooth muscle cells&#10;B)Immunoglobulin A on basophils and mast cells&#10;C)Immunoglobulin A on neutrophils and eosinophils&#10;D)Immunoglobulin E on basophils and mast cells&#10;E)Immunoglobulin E on neutrophils and eosinophils

Accepted Answer

Immediate hypersensitivity responses are primarily the result of liberation of vasoactive substances, such as histamine, leukotrienes, and prostaglandins, by the action of immunoglobulin E (IgE) on basophils and mast cells. IgE antibody is produced by B lymphocytes and binds to high-affinity receptors on the surface of basophils and mast cells. When an allergen binds to the IgE antibody, it triggers the release of these vasoactive substances, leading to immediate hypersensitivity reactions.

Question 5

Presentation of antigen on MHC-I by a target cell will result in which of the following?&#10;A)Generation of antibodies&#10;B)Activation of cytotoxic T cells&#10;C)Increase in phagocytosis&#10;D)Release of histamine by mast cells

Accepted Answer

Presentation of antigen on MHC-I by a target cell will result in activation of cytotoxic T cells. These T cells recognize and bind to the antigen-MHC complex and then proceed to kill the target cell. Antibodies are not generated in this process, and there is no increase in phagocytosis or release of histamine by mast cells.

Question 6

The marking of an invading microbe with immunoglobulin G and complement to facilitate recognition is referred to as which of the following?&#10;A)Chemokinesis&#10;B)Opsonization&#10;C)Phagolysosome fusion&#10;D)Signal transduction

Accepted Answer

The marking of an invading microbe with immunoglobulin G and complement to facilitate recognition is referred to as Opsonization.

Question 7

Which of the following are components of the innate immune system?&#10;A)Skin, natural killer cells, gastric acid, mannose receptors, alternative pathway of complement&#10;B)T lymphocytes, integrins, plasma cells, immunoglobulin D&#10;C)Endothelial glycocalyx, Fc receptors, major basic protein, MHC class II&#10;D)Mast cells, immunoglobulin E receptors, thrombin, perforin&#10;E)B lymphocytes, basophils, dendritic cells, granzyme B

Accepted Answer

The components listed in choice A are all part of the innate immune system.

Question 8

What causes the release of histamine in an allergic reaction?&#10;A)The binding of IgM to basophils&#10;B)The binding of IgE to mast cells&#10;C)The release of histamine by T helper cells&#10;D)The free radical stimulation of endothelial cells

Accepted Answer

Histamine is released in an allergic reaction when allergen-specific IgE antibodies on the surface of mast cells bind to the allergen, triggering degranulation and the release of histamine.

Question 9

Circulating antibodies are secreted mainly by which of the following?&#10;A)T helper lymphocytes&#10;B)T suppressor lymphocytes&#10;C)Dormant B lymphocytes&#10;D)Plasma cells&#10;E)T killer lymphocytes

Accepted Answer

Circulating antibodies are secreted by plasma cells, which are the mature effector cells of B lymphocytes. T helper lymphocytes provide help to B cells for antibody production, but they do not secrete antibodies themselves. T suppressor lymphocytes regulate immune responses by suppressing the activity of other immune cells, but they do not secrete antibodies. Dormant B lymphocytes are not actively producing antibodies. T killer lymphocytes are involved in cell-mediated immunity and do not secrete antibodies.

Question 10

What occurs following presentation of antigen by an infected cell?&#10;A)Generation of antibodies&#10;B)Activation of cytotoxic T cells&#10;C)Increase in phagocytosis&#10;D)Release of histamine by mast cells

Accepted Answer

Presentation of antigen by an infected cell leads to activation of cytotoxic T cells, which can then target and eliminate the infected cell. This is an important mechanism for fighting intracellular pathogens.

Question 11

Which subtype of lymphocytes produces lymphokines that direct their own cellular proliferation as well as the proliferation and differentiation of other immune cells?&#10;A)Large granular lymphocytes&#10;B)B cells&#10;C)Cytotoxic T cells&#10;D)T helper cells&#10;E)Natural killer cells

Accepted Answer

The answer of Which subtype of lymphocytes produces lymphokines that...

Question 12

T cell receptors are able to bind which of the following?&#10;A)Intact antigen&#10;B)Free antigenic peptides&#10;C)Peptides in the context of MHC proteins&#10;D)Chemokines

Accepted Answer

The answer of T cell receptors are able to bind...

Deck 35: Resistance of the Body to Infection: Ii Immunity and Allergy