Inhibition of Natural Killer Cell Activity by Antigen‐Antibody Complexes

The natural killer (NK) cell activity of human peripheral blood mononuclear cells was found to be inhibited by precipitated tetanus toxoid anti‐tetanus toxoid complexes (Te/ aTe) as well as soluble Te/aTe, Preincubation of the immune complexes with protein A decreased the inhibition of NK cell activity. When mononuclear cells were preincubated with interferon (IF) or interleukin 2 (II‐2) before incubation with Te/aTe, the immune complex‐induced inhibition was decreased, while IF or II‐2 added after incubation with the immune complexes had no effect. Using NK cell‐enriched suspensions in a single cell agarose assay, the immune complexes were shown to inhibit NK cell activity by inhibiting the formation of effector/target cell conjugates.