HTLV seroreactivity in Italian intravenous drug addicts is primarily due to HTLV-II infection.

To the Editor. — Over the last 5 years we have tested more than 3000 serum samples, collected from subjects at risk for retroviral infections, for the presence of antibodies to human T-cell lymphotropic virus type 1 (HTLV-I).1Reactivity was observed in approximately 10% of samples using viral lysate-based assays, but HTLV-I seropositivity could not be confirmed by Western blot analysis. The immunoreactivity was limited to the gag-encoded p19 and p24 proteins with varying intensity of the bands. Following the US Public Health Service guidelines for HTLV-I seropositivity,2all these samples were classified as HTLV-I indeterminate. We further investigated HTLV reactivity in 152 Italian intravenous drug addicts (IVDA) using synthetic antigens. All subjects were seropositive to human immunodeficiency virus type 1 (HIV-1) and attended a methadone maintenance clinic in the northwest district of Milan. Most had a history of sexual promiscuity, frequent needle sharing, and long-term drug addiction.