21. The Immune System

Which of the following conditions may lead to the development of autoimmunity?

a. Self antigens not previously encountered by T cells are released into the circulation.

b. Foreign antigens mimic self antigens.

c. Cells may inappropriately display class II MHC molecules.

d. Certain pathogens nonspecifically activate B cells.

e. All of the above are correct.

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.

b. The secondary immune response is mediated by plasma cells.

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? (Connects to Chapter 19)

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

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

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

a. TH cells; macrophages

b. neutrophils; TH cells

c. B cells; TC cells

d. mast cells; TH cells

Which of the following is NOT a consequence of the immune system lacking an immune tolerance?

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

d. Cancer cells are destroyed by NK cells, TC cells, and macrophages.

Complement proteins are crucial for stimulating phagocytes to clear immune complexes. Predict what type of hypersensitivity disorder might result from complement deficiencies. Explain what other consequences might arise from a complement deficiency.

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

e. Dendritic cells may activate both TH and TC cells.

The most important function of peripheral tolerance is to:

When naïve B cells are activated, they differentiate into:

a. plasma cells.

b. memory cells.

c. both a and b.

d. none of the above.

On which type(s) of cells are class I MHC molecules located?

a. Antigen-presenting cells only

b. B cells only

c. All nucleated body cells

d. Antigen-presenting cells and B cells

Fill in the blanks: Class I MHC molecules display_____antigens and activate_____cells. Class II MHC molecules display _____antigens and activate_____cells.