Antibody-Dependent Lymphoid Cell-Mediated Cytotoxicity: Role of Lymphocytes Bearing a Receptor for Complement

Abstract

Abstract It has been shown previously that the destruction of antibody-coated burro erythrocytes in vitro can be caused by lymphoid cells from nonimmune donors. Furthermore, thymus-derived lymphocytes are not required for such lysis. In this report we provide evidence that a subclass of bone marrow-derived lymphocytes bearing a Mg++-independent complement receptor is largely responsible for the cytotoxic activity of mouse spleen cell populations. Thus, removal of complement receptor lymphocytes (CRL) by rosetts formation and subsequent sedimentation by density gradient ultracentrifugation diminishes the lytic activity of the remaining cells. Moreover, recovery and dissociation of these rosettes yields a purified population of CRL which have heightened cytotoxic activity. Nonetheless, not all CRL are equally active. Thus, although the frequency of CRL in lymph node cell populations is approximately one-half that of spleen cell populations, lymph node cells have very little activity. Furthermore, passage of spleen cells over rayon fiber columns diminishes cytotoxic activity by approximately 75% although the CRL frequency is diminished by only 30%. In the mouse spleen the cell type primarily involved in antibody-dependent cell-mediated lysis therefore appears to be a member of a subset of the complement receptor bearing bone marrow-derived lymphocytes.