Transmission of human T-cell leukemia virus (HTLV-I) by blood transfusion: demonstration of proviral DNA in recipients' blood lymphocytes.

Human T-cell clones bearing antigens encoded by human T-cell leukemia/lymphoma virus (HTLV-I) were isolated from 6 patients who produced antibodies against HTLV-I after having received anti-HTLV-I-positive blood units containing cell components. On the other hand, it was not possible to isolate clonal cells carrying viral antigens from the recipients who did not produce antibodies. The clonal cell lines had the same surface markers as neoplastic cells of adult T-cell leukemia and had the HLA phenotype of the recipients themselves. Proviral DNA of HTLV-I was demonstrated in each of the clonal cell lines. The site of integration was different in each case even if the clones were derived from the same recipient. These results indicate that blood transfusion can cause persistent HTLV-I infection.