Human immunodeficiency virus (HIV) affects the immune response. The primary change brought about is:: (A) A gammaglobulinemia, (B) Defect in cell-mediated immunity, (C) Defect in complement system, (D) Defect in natural killer cells
Answer is B. HIV infects CD4 (helper) T-lymphocytes, macrophages and monocytes and leads to cell-mediated immune deficiency which predisposes to opportunistic infections and malignancies.