lymphocyte

A lymphocyte is one of the five types of white blood cell, and the one that runs the adaptive immune response — the specific, remembering one. Its two kinds split by job: B cells make antibodies that stick to one specific antigen, and T cells help the rest of the response and destroy body cells that a microbe has taken over. Both kinds leave memory cells behind after the response ends, which is why the second meeting with the same antigen is fast and strong. Lymphocytes are not the only white cells that do immune work: the phagocytes engulf and digest, and they work in the innate response, which keeps no memory — and a natural killer cell is a lymphocyte of that innate response too. The exam separates them by the verb: lymphocytes target and remember, phagocytes engulf. Lymphocytes are also the cells the lymph nodes and the spleen hold.