What is the function of B-cells?

• A. Produce cytokines to recruit other immune cells.
• B. Synthesize and release antibodies, attack pathogens directly.
• C. Present antigens to T cells.
• D. Engulf and digest microbes.

Answer: (B)

B cells are central to humoral immunity. Their primary function is to synthesize and secrete antibodies that are tailored to specific antigens. Once activated, B cells differentiate into plasma cells that produce large amounts of antibodies. These antibodies bind to pathogens or toxins, neutralizing them, blocking their ability to infect host cells, and marking them for destruction by other immune cells (opsonization and complement activation). While B cells can present antigens to helper T cells and secrete cytokines to influence the response, the defining action is antibody production that directly targets pathogens in body fluids. Roles like engulfing microbes are carried out mainly by phagocytes.