Which statement best describes the role of helper T cells (CD4+ T cells) in the immune response?

• A. They directly kill infected cells.
• B. They produce antibodies.
• C. They coordinate immune responses by secreting cytokines.
• D. They phagocytose pathogens.

Answer: (C)

Helper T cells act as the conductors of the adaptive immune response. After their T cell receptor recognizes antigen presented by MHC class II on an antigen-presenting cell, they become activated and release a diverse set of cytokines. These cytokines coordinate the immune reaction by signaling and guiding other immune cells: they help B cells mature and undergo class switching to produce different antibodies, they assist cytotoxic T cells in killing infected cells, and they enhance the killing and antimicrobial activities of macrophages. This orchestrating role is why the description of helper T cells as coordinating immune responses by secreting cytokines is the best match. Direct killing is done by cytotoxic T cells, antibody production is carried out by B cells, and phagocytosis is performed by phagocytes like macrophages, not by helper T cells themselves.