15. What is the main cause of immunodeficiency in AIDS patients?
A) Malnutrition
B) Human immunodeficiency virus (HIV) infection
C) Deficiency of C1 inhibitor
D) Failure of helper T cells to produce gamma interferon

16. Which component of the immune system is highly suppressed inAIDS patients?
A) Immunity
B) B cells
C) Cell-mediated immunity
D) T cells

17. Which organs are affected in hereditary angioedema?
A) Liver and kidneys
B) Heart and lungs
C) Larynx and several other organs
D) Blood cell precursors

18. What is the effect of liver failure on the immune system?
A) Temporary suppression of delayed hypersensitivity
B) Reduction in the synthesis of complement proteins
C) Reduction in the supply of amino acids
D) Defective adhesion of leukocytes to microbes