Antibodies against three purified proteins of the human type C retrovirus, human T-cell leukemia-lymphoma virus, in adult T-cell leukemia-lymphoma patients and healthy Blacks from the Caribbean.

Six black patients of Caribbean origin with adult T-cell leukemia-lymphoma, 18 of their healthy family members and relatives, and 337 healthy black individuals from the Caribbean were investigated for the presence of serum antibodies against human T-cell leukemia-lymphoma virus (HTLV). Three distinct structural proteins of this virus with molecular weights of 24,000, 19,000, and 15,000 were purified, radiolabeled, and used in radioimmune precipitation assays. Five of the patients, three of the family members (two of them spouses), and 11 of the normals had specific antibodies against at least the proteins with molecular weights of 24,000 and 19,000. High antibody titers against these proteins were often associated with antibodies against the protein with a molecular weight of 15,000. In all cases, antibody titers against this protein were considerably lower than those against the proteins with molecular weights of 24,000 and 19,000. HTLV is highly associated with Caribbean adult T-cell leukemia-lymphoma and is also endemic among the normal Caribbean population. By comparison of the frequencies of anti-HTLV positives among family members of patients and the normal population, we conclude that infection by HTLV occurs in a horizontal way and at least in the West Indian black and Japanese population probably without a requirement for uncommon genetic factors.