Serum levels of soluble interleukin-2 receptors (sIL-2R) were measured in 105 HIV-seropositive individuals simultaneously with T cell subsets and activated T cells (CD3+ and HLA-DR+). Significantly elevated levels of serum sIL-2R were found (564 +/- 259 U/ml versus 258 +/- 87 U/ml in 70 controls, p less than 0.001), as well as increased numbers of activated T cells (mean numbers, 579/microliters in the patients versus 113/microliters in 26 controls, p less than 0.0001). Correlation analysis did not disclose any significant association between elevated sIL-2R and increased activated T cells, nor with decreased CD4+ lymphocytes. These data suggest that sIL-2R in HIV infection do not emanate from activated T cells and are not linked to CD4+ cell loss.