Helper T cells primarily function to?

• A. Stimulate T and B cells
• B. Kill infected cells
• C. Produce antibodies
• D. Engulf pathogens

Answer: (A)

Helper T cells coordinate the immune response by recognizing antigen presented on MHC class II molecules on professional antigen-presenting cells and then releasing cytokines that activate other immune cells. This signaling helps stimulate both arms of adaptive immunity: it promotes the proliferation and activation of cytotoxic T cells to target infected cells and it assists B cells in becoming antibody-secreting plasma cells (and in undergoing class switching and affinity maturation). They don’t themselves kill infected cells, produce antibodies, or engulf pathogens—those roles belong to cytotoxic T cells, B cells, and phagocytes, respectively.