HUMAN-IMMUNODEFICIENCY-VIRUS (HIV) NEF-SPECIFIC CYTOTOXIC T-LYMPHOCYTES IN NONINFECTED HETEROSEXUAL CONTACT OF HIV-INFECTED PATIENTS

We report on the detection of HIV-specific cytotoxic T lymphocytes (CT L) among 23 regular partners of HIV-infected individuals. 15 of the 46 individuals enrolled in the study were positive for HLA-A2.1 typing. Among the 23 contacts studied, 7 were seropositive and 16 were seroneg ative on repeated tests. None of the 16 seronegative contacts were pos itive for p24 antigenemia nor were they positive by the lymphocytes co culture assay, although, in two instances HIV-1 DNA could be detected by PCR(in one case using a gag SK 38/39 primer, and in the other using a primer for the pol P3/P4 primer). These two individuals remained se ronegative for 18 and 36 mo, respectively. HIV-specific cytotoxicity w as performed in the 15 HLA-A2.1 subjects (7 indexes, 2 seropositive co ntacts, and 6 seronegative contacts) and in 4 HLA-matched HIV negative donors. CTL specific for env, gag, or nef proteins could not be detec ted in unstimulated bulk cultures of peripheral blood lymphocytes in a ny of the six seronegative contacts. However, using a limiting dilutio n assay we found an usually high frequency of HIV nef-specific CTL in six seronegative contacts studied. The frequency of CTL precursors (CT Lp) for HIV env and gag was very similar to that observed in seronegat ive HLA-matched healthy donors. Because no presence of HIV could be de monstrated in these individuals, these findings argue against the poss ibility of a silent HIV infection and suggest that a CTL response agai nst nef may be involved in a rapid and effective clearance of the viru s after sexual exposure.