21. Immune System

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

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.

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.