New observations regarding killing of fibroblasts infected with herpes simplex virus: cooperation between elutable...

With a standard chromium release assay, natural killing (NK) activity of peripheral mononuclear cells (PMCs) from 28 individuals was compared based on the ability of sera to support antibody-dependent cell-mediated cytotoxicity (ADCC) for cells infected with herpes simplex virus (HSV). PMCs from all 20 individuals whose sera produced ADCC were capable of killing HSV-infected cells compared with none of the PMCs from the eight individuals whose sera did not produce ADCC (mean specific release, 33.2% vs. 6.8%). Results could not be explained by contaminating serum in the assay or by ineffective NK by the PMCs from the eight negative subjects because many of them killed the k562 myeloid cell line as effectively as PMCs from other individuals. In addition, NK could be eliminated by preincubation of effector cells at 37 C, and the capacity to kill by PMCs could be reconstituted by incubation in serum. Killing was more a function of source of serum rather than source of cells.