Deck 16: Specific Host Defense Mechanisms: an Introduction to Immunology

Question 1

Of the following, which is the least likely to be involved in CMI?
a. antibodies
b. cytokines
c. macrophages
d. T cells

Answer 1

Antibody-mediated immunity is otherwise called humoral immunity. This is one of the major arms of immune system. Antibodies play a main role in this arm of immune system. The other arm of immune system is called cell-mediated immunity. It is also called CMI. Many types of cells take part in this immunity which includes T cells, B cells, and NK cells. But antibodies play minor role and sometimes no role in this immunity. Hence, the option (a) is correct.
Cytokines are involved in the cell-mediated immune responses. Cytokines are proteins or chemical messages by which cells of the immune system communicate with one another. In cases of injury the cytokines attract the leukocytes to the site of injury and are called as chemokines. Hence, the option (b) is incorrect.
Macrophages are derived from monocytes. Monocytes are white blood cells. They play a major role in CMI. Macrophage engulfs the pathogen and digests it partially. On the surface of the macrophage the fragments of the pathogen are displayed. So, macrophages are antigen-presenting cells. T H cell get attached to the surface of the macrophage and release cytokines which in turn induces effector cell to bind to a target cell. Hence, the option (c) is not correct.
T cells are major cell type which takes part in the CMI. They are T lymphocytes produced by lymphoid stem cells of bone marrow. Main function of T cells is production of cytokines. The T cells are of two types. They are helper T cells and cytotoxic T cells.
Hence, the correct option is (a)

Question 2

Antibodies are secreted by:
a. basophils.
b. macrophages.
c. plasma cells.
d. T cells.

Answer 2

Plasma cells secrete antibodies. Antibodies are produced by plasma cells when B cells are stimulated by antigens. Hence, plasma cells are derived from B lymphocytes. Antibodies are produced by the stimulation of immune system by antigens. Antibodies have main role in humoral immunity and the humoral antibodies stay in the body secretions like plasma and lymph. These antibodies protect the body from the specific pathogen which induced their production. Hence, the option (c) is correct.
Basophils are a type of leukocytes. They do not produce antibodies. They have part in allergic inflammatory reactions. It also helps in vasodilation as it has histamine. IgE binds to basophils as it has surface receptors for it. Hence, the option (a) is incorrect.
Macrophages are derived form of monocytes which are leukocytes. The macrophages are efficient phagocytes. But they do not produce antibodies. But they have part in the stimulation of lymphocytes and other cells of immune system. The M1 and the M2 macrophages stimulate the production of antibodies. Hence, the option (b) is incorrect.
T cells do not secrete antibodies. T cells are T lymphocytes. It plays a major role in cell-mediated immunity. There are two types of T cells. They are helper T cells and cytotoxic T cells. The helper T cells known as T H 2 cells help in the B lymphocytes activation and differentiate them into plasma cells. Hence, the option (d) is incorrect.
Hence, the correct option is (c)

Question 3

Humoral immunity involves all the following except:
a. antibodies.
b. antigens.
c. NK cells.
d. plasma cells.

Answer 3

NK cells are natural killer cells. They are cytotoxic lymphocytes. It plays a major role in cell-activated immune system. They kill those host cells which have the pathogens inside them and also foreign cells. They do not have T-cell or B-cell surface markers and do not have antigen response proliferation. They do not recognize the specific antigen. Their action does not depend on antibodies. So, the NK cells do not involve in humoral immunity. But they have receptors for Fc region of IgE antibodies and hence they kill the target cells coated with antibodies. Hence, the option (c) is the correct option.
In humoral activity, antibodies are produced by B cells in response to the presence of antigens. Antibodies are proteins called immunoglobulins. These immunoglobulins have specificity for an antigen. Antibodies are present in blood, saliva, tears, and colostrum. Hence, the option (a) is not correct.
Antigens are foreign substances. They are antibody generating substances. They are large proteins. Humoral immunity is mainly involved in the production of antibodies due to the presence of antigens. The substances which stimulate the antibody production are called antigenic substances. Hence, the option (b) is incorrect.
Plasma cells are involved in the humoral immunity. The plasma cells secrete antibodies which are produced in the humoral immunity. These plasma cells are formed from the B lymphocytes. In response to antigen, the antibodies are secreted by plasma cells. When the entire antigen by the pathogen is used up, the antibodies decrease in the blood. This is because of the death of the plasma cells. Hence, the option (d) is incorrect.
Hence, the correct option is (c)

Question 4

Immunity that develops as a result of an actual infection is called:
a. artificial active acquired immunity.
b. artificial passive acquired immunity.
c. natural active acquired immunity.
d. natural passive acquired immunity.

Question 5

Artificial passive acquired immunity would result from:
a. having the measles.
b. ingesting colostrum.
c. receiving a gamma globulin injection.
d. receiving a vaccine.

Question 6

The vaccines that are used to protect people from diphtheria and tetanus are:
a. antitoxins.
b. attenuated vaccines.
c. inactivated vaccines.
d. toxoids.

Question 7

Natural passive acquired immunity would result from:
a. having the measles.
b. ingesting colostrum.
c. receiving a gamma globulin injection.
d. receiving a vaccine.

Question 8

Which of the following statements about IgM is false?
a. IgM contains a J chain.
b. IgM has a total of 10 antigen-binding sites.
c. IgM is a pentamer.
d. IgM is a long-lived molecule.

Question 9

Which of the following could be an effect of type III hypersensitivity?
a. glomerulonephritis
b. rheumatoid arthritis
c. SLE
d. all of the above

Question 10

Most likely, immunology got its start in 1890 when these scientists discovered antibodies while developing a diphtheria antitoxin.
a. Edward Jenner and Louis Pasteur
b. Elie Metchnikoff and Robert Koch
c. Emil Behring and Kitasato Shibasaburo
d. Jonas Salk and Albert Sabin