Effect of lymphokines on natural killer cytotoxicity in patients with high risk of developing the acquired immune deficiency syndrome

Regulation of natural killer (NK) activity of peripheral blood mononuclear cells (PBMC) from patients with the acquired immune deficiency syndrome (AIDS) and from individuals at high risk of developing AIDS (R-AIDS) was studied. The response of untreated PBMC to the interferon inducer polyinosinic polycytidilic acid (Poly I:C) was lower in AIDS and R-AIDS than in normal controls and PBMC from R-AIDS were more susceptible to stimulation with lymphokine rich supernatants (Con A-SN, PHA-SN, lectin free IL-2) than AIDS and normal controls. To determine the role of the different T lymphocyte subsets in the regulation of NK activity, PBMC were selectively treated with monoclonal non-cytotoxic anti-Leu 2a and anti-Leu 3a antibodies and then stimulated with lymphokine rich supernatants. These results indicate that the effect of crude supernatants was the combination of opposite effects. Leu 2a-blocked R-AIDS-PBMC enhanced NK cytotoxicity when exposed to IL-2 rich supernatants whereas Leu 3a-blocked R-AIDS-PBMC suppressed the cytotoxic reaction.