Abstract
Repeated exposure to human immunodeficiency virus (HIV) does not always result in HIV infection, and several cohorts of HIV-exposed but uninfected (EU) individuals have been described. We studied T-helper and granule-dependent cytotoxic T-lymphocyte (CTL) activities in a group of 30 EU partners of HIV type 1 (HIV-1)-infected individuals. HIV-1-specific helper-T-cell activity was studied by measuring the levels of interleukin 2 (IL-2) produced by peripheral blood mononuclear cells (PBMCs) and the granule-dependent CTL activity by measuring the intracellular levels of perforin and granzyme B expression in CD8+ T cells after stimulation with gag p24 antigen. Elevated IL-2 production by PBMCs after p24 stimulation occurred in EU individuals. The levels of perforin and granzyme B expression in CD8+ T cells were also higher among EU individuals than among healthy controls. HIV-specific helper-T-cell and granule-dependent CTL activities inversely correlated with the time since the last unprotected sexual exposure in these individuals. In our cohort, activation of T-helper and granule-dependent CTL activities against HIV might be due to unprotected sexual contact. These results indicate that HIV-1-specific T-cell responses could play a role in protection against acquiring infection in this cohort of EU individuals.