Natural killer cells in guinea pig spleen bear Fc receptors.

Abstract

AbstractThe phenomenon of natural cytotoxicity or spontaneous cell‐mediated cytotoxicity (SCMC) was investigated in guinea pigs and compared with two other in vitro cytotoxicity reactions: mitogen‐induced cellular cytotoxicity (MICC) and antibody‐dependent cellular cytotoxicity (ADCC). The same xenogeneic target cells were employed in all three cytotoxicity assays.Organ distribution studies revealed that SCMC effector cell activity was present in spleen and peripheral blood but not in thymocytes. Bone marrow cells possessed low levels of SCMC effector cell activity. The organ distribution of effector cell activities for MICC and ADCC paralleled that for SCMC. Studies of the cell surface characteristics of the SCMC effector cell revealed that spleen cells nonadherent to antigen‐antibody but not to antigen‐F(ab')2 antibody‐coated surfaces possessed markedly reduced SCMC effector cell activity. In addition, spleen cells depleted of Fc receptor‐bearing cells by EA rosetting also possessed diminished SCMC effector cell activity, while cell populations enriched in Fc receptorbearing cells by EA resetting possessed enhanced SCMC effector cell activity. These fractionation techniques had similar effects on MICC and ADCC effector cell activity. Depletion of adherent spleen cells including macrophages by nylon wool column passage resulted in a population of cells with enhanced SCMC, MICC, and ADCC effector cell activity.Thus, in guinea pig spleen the effector cells mediating SCMC were shown to belong to a population of nonadherent Fc receptor‐bearing lymphocytes possessing several cytotoxic capabilities including the potential of mediating MICC and ADCC.