Spontaneous cytotoxicity of human peripheral blood mononuclear cells for the lymphoblastoid cell line CCRF-CEM: augmentation by bacterial lipopolysaccharide

Spontaneous cell-mediated cytotoxicity (SCMC) of human peripheral blood mononuclear cells for a poor target, CCRF-CEM, a lymphoblastoid cell line, was rapidly and markedly elevated by E. coli lipopolysaccharide (LPS). SCMC for K562, a myeloid cell line sensitive to SCMC, was only slightly elevated by LPS. The cytotoxicities of both adherent and non-adherent mononuclear cells for CCRF-CEM were elevated. A response to LPS was found in FcγR-positive and FcγR-negative T cells. LPS increased the binding of non-adherent cells to both targets, but analysis of the binding suggests that a subsequent step, either triggering of the cytotoxic mechanisms or susceptibility of the target was the basis for the increased SCMC.