ANTIBODY-DEPENDENT LYMPHOCYTE-MEDIATED CYTOTOXICITY (Ab-LMC), DEFINITION OF THE “K CELL” IN THE RAT

The nature and membrane characteristics of the "K cell" of antibody-dependent lymphocyte-mediated cytotoxicity (Ab-LMC) were investigated in a widely used rat model of transplantation. Treatment of sensitized effector cell populations with anti-immunoglobulin and complement eliminated K cell cytotoxicity without diminishing the component of T cell-mediated injury. EA and EAC depletion experiments, although demonstrating no loss of K cell cytotoxicity after removal of complement receptor-bearing lymphocytes, produced a marked abrogation of cytotoxicity following the removal of the Fc receptor-bearing lymphocyte pool. Studies on phagocytic properties showed K cell activity to be shared by an adherent as well as a nonadherent cell population. Thus, the Fc receptor emerged as the only constant surface marker of the rat K cell in Ab-LMC.