Lymphoid cells as effectors of immunologic cytolysis.

Two classes of cytotoxic lymphocytes are described. One is composed of cytotoxic T lymphocytes (CTL), which have antigen specificity derived from prior immunization. The lymphocytes of the other class--the K cells--derive their limited specificity from affinity for antibodies on the surface of the target cells. Together these two lymphocyte classes provide a broad-spectrum defense against unwanted foreign and mutant cells.