21. The Immune System

What are the three classes of lymphocytes, and where does each class originate?

A decrease in which population of lymphocytes would impair all aspects of an immune response?

(a) Cytotoxic T cells

(b) Helper T cells

(c) Regulatory T cells

(d) B cells

(e) Plasma cells

Perforins are proteins associated with the activity of

(a) T cells

(b) B cells

(c) NK cells

(d) Plasma cells

Where do T cells undergo central tolerance selection?

What is immunological tolerance?

Explain why a patient with AIDS due to HIV is at an increased risk of infection and of developing certain cancers.

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

The secondary immune response is mediated by plasma cells.

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?