Interleukin 2 augmentation of natural killer cell activity in homosexual men with acquired immune deficiency syndrome

Natural killer cell activity of peripheral blood mononuclear cells against K562 myeloid cells was studied in 8 normal heterosexual men, 5 healthy homosexual men, and 11 homosexual men with acquired immune deficiency syndrome. The overall natural killer cell activity was lower in healthy homosexual men and in homosexual men with acquired immune deficiency syndrome. Peripheral blood mononuclear cells from four normal heterosexual men were preincubated overnight in complete medium supplemented with various concentrations of lectin-free interleukin 2 lacking interferon. Cells from these cultures exhibited a dose-dependent augmentation of natural killer cell activity. Peripheral blood mononuclear cells obtained from 8 normal heterosexuals, 5 healthy homosexuals, and 11 homosexual men with acquired immune deficiency syndrome were preincubated overnight in complete medium supplemented with 20% interleukin 2. Natural killer cell activity cultured in 20% interleukin 2 increased to 78.4 +/- 8.4 (mean +/- standard deviation) from 30.8 +/- 11.0 in normal heterosexual men, to 68.3 +/- 17.6 from 16.8 +/- 13.6 in healthy homosexual men and to 49.3 +/- 15.3 from 11.6 +/- 6.1 in homosexual men with acquired immune deficiency syndrome at a 100:1 effector/target cell ratio. These results suggest that interleukin 2 is capable of directly stimulating natural cell-mediated cytotoxicity. Consideration of the use of interleukin 2 as a potential therapeutic agent to modify immune responses in disorders such as acquired immune deficiency syndrome appears warranted.