Which T-cell subset is CD4+ and helps activate other immune cells?

• A. Cytotoxic T cells
• B. B cells
• C. Helper T cells
• D. Antigen-presenting cells

Answer: (C)

Helper T cells are CD4+ and act as the central coordinators of the immune response. They release cytokines that activate and support other immune cells, such as helping B cells mature into antibody-secreting plasma cells, enhancing cytotoxic T cell responses, and activating macrophages to kill pathogens more effectively. They recognize antigens presented by MHC class II on antigen-presenting cells, which triggers these helper signals. The other options don’t fit this role: cytotoxic T cells are CD8+ and kill infected cells directly; B cells are not T cells and require help to become antibody producers; antigen-presenting cells present antigen but are not the CD4+ T-cell subset.