Which lymphocytes have a high affinity for HIV?

• A. B-lymphocytes
• B. Phagocytes
• C. T-cytotoxic lymphocytes
• D. T-helper lymphocytes

Answer: (D)

HIV targets cells that display the CD4 receptor, and among lymphocytes the cells with the most CD4 are the T-helper lymphocytes. The viral envelope gp120 binds to CD4 and then uses co-receptors (CCR5 or CXCR4) to fuse with the cell and enter it. Because T-helper cells carry CD4, they are the primary targets and reservoirs for HIV replication. B-lymphocytes generally don’t express CD4 as a key entry point, phagocytes like macrophages can be infected but aren’t the main high-affinity targets, and cytotoxic T cells (CD8+) are critical effector cells rather than the main cells HIV preferentially infects. The loss of T-helper cells explains why HIV progression leads to weakened immune coordination over time.