Serum-induced enhancement of peripheral blood mononuclear cell mediated cytotoxicity towards human target cells in systemic lupus erythematosus.

Sera from 6 out of 18 patients with systemic lupus erythematosus (SLE) were found to be capable of producing marked increases of cytotoxicity in several established human target cell lines when co-cultured with normal human peripheral blood mononuclear cells (PBM). Fractionation studies indicated that the cytotoxicity-inducing activity resided in IgG containing fractions and that the effector cells were Fc-receptor positive. By contrast, sera from 27 normal controls produced little or no cytotoxicity when similarly co-cultured with the same target cell lines and normal PBM. Any slight reactivity that occasionally occurred against a single cell line was, on serum fractionation, either labile or associated with albumen containing fractions. These findings raise the possibility that antibody-dependent cellular cytotoxicity could provide an additional pathogenetic mechanism in patients with SLE.