The course of human immunodeficiency virus (HIV) infection progresses from an acute infection, through a prolonged asymptomatic phase, to an immunocompromised state. Some of the possible mechanisms underlying immune dysfunction include decreased HIV-specific cytotoxic T lymphocyte (CTL) activity, increased suppressor T cells, and/or increased HIV load. However, no study has been carried out to correlate all these factors. In this study, 26 patients showed > 3 log DNA copy number/10(6) CD4+ T cells, and seven patients had < 3 log DNA copy/10(6) CD4+ T cells. Patients with higher virus load had greater than 15% (19-45%) CD8+ CD11+ T cells. HIV-1 envelope-specific, HLA-restricted CTL activity (> 10%) was observed in 11 of 25 asymptomatic patients, and the remaining 14 patients lacked CTL activity (< 10%) in bulk assay. Although CTL activity was undetectable in these individuals, there was no significant difference in the frequency of activated CTL and their precursors in limiting dilution analysis. The patients with undetectable CTL activity had a higher percentage of CD8+ CD11+ T cells and a higher HIV-1 DNA copy number/million CD4+ T cells. Each of these parameters were significantly correlated with CD4+ T-cell numbers. The inverse relationship of CD8+ CD11+ T cells and virus load with HIV-specific CTL activity observed in this study may be one of the underlying factors which determines the course of HIV infection.