HIV directly infects T-cells. Why is this problematic for cell-mediated immunity?

• A. T-cells are responsible for phagocytosis, so their loss reduces pathogen engulfment.
• B. T-cells are essential for activating other immune cells, so their loss impairs the body's ability to mount effective cell-mediated responses.
• C. T-cells neutralize toxins directly, so their infection allows toxins to accumulate.
• D. T-cells produce antibodies, so their infection prevents antibody-mediated immunity.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the role of T-cells in the immune system. T-cells are a type of lymphocyte that play a central role in cell-mediated immunity by activating other immune cells and coordinating the immune response.
2. Step 2: Recognize that HIV infects T-cells, specifically the CD4+ helper T-cells, which are crucial for signaling and activating other immune cells such as cytotoxic T-cells and macrophages.
3. Step 3: Analyze why the loss of T-cells is problematic. Since T-cells activate other immune cells, their depletion leads to a weakened immune response, impairing the body's ability to fight infections effectively.
4. Step 4: Differentiate T-cells from other immune cells. For example, phagocytosis is primarily performed by macrophages and neutrophils, not T-cells; antibody production is the role of B-cells, not T-cells.
5. Step 5: Conclude that the key problem with HIV infecting T-cells is the impairment of cell-mediated immunity due to the loss of T-cell activation functions, which compromises the immune system's ability to mount an effective response.