Final answer:
HIV primarily attacks and destroys T lymphocytes (helper T cells), leading to a loss of cell-mediated immunity.
Step-by-step explanation:
HIV primarily attacks and destroys T lymphocytes (also known as helper T cells). Helper T cells are a type of lymphocyte that play a crucial role in regulating the immune response. When HIV infects and destroys these cells, it leads to a loss of cell-mediated immunity and makes the body more susceptible to opportunistic infections.