Natural killer cell responses in homosexual men with early HIV infection

Natural killer (NK) cells may be of significance in host defense against viral infections. In the present study, NK cell function was examined in relation to different phases of human immunodeficiency virus (HIV) infection. Peripheral blood mononuclear cells were tested for NK cell activity using K562 cell targets in a 51Cr-release assay. NK cell responses of 26 HIV-seronegative homosexual men were not significantly different from those of 30 heterosexual controls. NK activity was significantly lower in cells from 32 homosexual men with documented, early-phase HIV infection (average of 14 months; range of 3-27 months) as compared with that of seronegative men. The NK cell response decreased with time, since men within the first year of infection (n = 15; average of 7.8 months; range of 3-12 months) had greater NK cell activity than did those with longer duration of infection (n = 17; average of 18.3 months; range of 13-27 months). The decrease in NK cell activity did not correlate with altered numbers of cells bearing CD16 (NK) markers in these subjects. NK cell-mediated lysis and cell numbers were most severely depressed in a separate group of HIV-seropositive men who had acquired immune deficiency syndrome (AIDS). In vitro treatment with alpha-interferon (alpha-IFN) significantly enhanced NK activity of effector cells obtained from men within the first year of HIV infection but not in those with longer-term infection. Our results indicate that NK cell function decreases over time within the first 2 years of HIV infection in homosexual men, and is lowest in HIV-seropositive men with overt AIDS.(ABSTRACT TRUNCATED AT 250 WORDS)