21. The Immune System

How does a cytotoxic T cell destroy another cell displaying antigens bound to class I MHC proteins?

Although the adaptive immune system has two arms, it has been said, 'no T cells, no immunity.' Explain.

Mr. White developed neutropenia as a consequence of cancer chemotherapy, which destroyed much of his bone marrow. What other components of the immune system would be harmed by bone marrow destruction? Would you expect his hematocrit to be elevated or decreased? What effects would you expect to see from this change in hematocrit?

Mr. James, an 80-year-old man, is grumbling about having to receive a flu shot every year. Flu viruses have a high mutation rate (undergo rapid genetic changes), which results in the appearance of new proteins on the flu virus's 'coat.' How does this help explain the need to get a flu shot each year?

Blocking the antigen receptors on the surface of lymphocytes would interfere with

(a) Phagocytosis of the antigen

(b) That lymphocyte's ability to produce antibodies

(c) Antigen recognition

(d) The ability of the lymphocyte to present antigen

(e) Opsonization of the antigen

Differentiate between humoral and cellular adaptive immunity.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The immune response to a viral infection involves NK cells and different kinds of lymphocytes.

CD4 markers are associated with

(a) Cytotoxic T cells

(b) Regulatory T cells

(c) Helper T cells

(d) All of these

Type I hypersensitivity is due to release of inflammatory mediators from_____, and type IV hypersensitivity is due to the actions of_____.

a. T_H cells; macrophages

b. neutrophils; T_H cells

c. B cells; T_C cells

d. mast cells; T_H cells

Lymphocytes that develop immunocompetence in the bone marrow are:

a. T lymphocytes

b. B lymphocytes

c. NK cells

d. B and T lymphocytes

Mark the following statements as true or false. If a statement is false, correct is to make a true statement.

In the primary immune response, the lag phase lasts about 5 days, during which time B cells proliferate and differentiate.