ABSTRACT
K cell activity 1 has been described as the ability of certain mononuclear cells to kill target cells sensitized by antibody. They do so through their Fc receptor that recognizes the Fc part of bound, but not free, antibody. 2 Any nucleated cell capable of division may be destroyed by such an effector mechanism. Target structures may be histocompatiblity antigens, viral antigens, differentiation antigens, membrane determinants as receptors, or haptens artificially introduced at the membrane. Human K cell activity may be elicited by human antibodies, or classically by rabbit antisera. Usually a 10−4 to 10−5 dilution of an appropriate antiserum would sensitize relevant target cells for optimal K cell activity. The effector cell is found in peripheral blood, spleen, peritoneal cavity, and inflammatory exudates, but not in bone marrow or tonsils.
