ObjectiveTo determine the serum levels of the soluble form of the CD30 (sCD30) activation molecule in the early phase of HIV-1 infection, and to investigate the possible correlation with evolution to AIDS.MethodssCD30 values were determined by an enzyme-linked immunosorbent assay (ELISA) on serum samples collected at the time of the first evidence of HIV-1 infection in 110 individuals with a median follow-up of 56 months (range, 12–88 months), at the A1 (74 cases) or A2 (36 cases) stages of the 1993 revised Centers for Disease Control and Prevention classification. The data were evaluated using established clinical and immunological parameters, including circulating CD4+ T-cell count. The controls were 110 blood donors and 51 HIV-1 -negative subjects belonging to groups at risk for HIV-1 infection.ResultsElevated sCD30 levels ( 20 U/ml) were found in 83.6% of HIV-1 -infected cases and in 47% of at-risk seronegatives. Data analysis revealed that HIV-1-infected patients with higher sCD30 levels (>35 U/ml) experienced faster disease progression (P= 0.0002). This was also the case in patients at the earliest stage (A1) of HIV infection (P= 0.0027). In these latter cases the predictive value of sCD30 was independent of the initial absolute number of circulating CD4+lymphocytes.ConclusionsSerum levels of sCD30 are increased in the large majority of patients in the early phase of HIV-1 infection and represent an indicator of progression to AIDS independent of other prognostic parameters.