The mechanism of K cell (antibody-dependent) cell mediated cytotoxicity II. Characteristics of the effector cell and morphological changes in the target cell

Abstract

K cells share certain physical characteristics with T [thymus-derived] cells. This had made it possible to apply standard cell purification techniques to be used for the enrichment of K cells. This has in turn enabled time lapse studies to be carried out at low cell density. In addition to the similar physical characteristics, K cells have a structure and movement similar to those of cytotoxic T cells. K cell cytotoxicity does no apparent damage to the K cell and each K cell is able to kill more than 1 target cell. Analysis of time lapse films of cytotoxicity of mouse P815 mastocytoma cells directly confirms 3 inferences on the mechanism of target cell death suggested by the kinetic data in the previous paper: contact itself does not appear to damage the target cell; target cell death usually begins within 15 min of K cell contact; cell death is an explosive event with zeiosis boiling of the cytoplasm. This phenomenon is similar to that observed with T cell cytotoxicity and quite different to changes seen during lysis by antibody and complement. Analysis of films of cytotoxicity of human MRC5 cells which are glass adherent showed that the K cell is in close apposition to the nucleus within 1 min of the 1st cytoplasmic changes (shrinkage).