Antigenicity of human T-cell leukemia virus-associated gp52: greater response in leukemia patients compared to healthy donors exposed to the virus.

Monoclonal antibody HT462 recognizes a human T-cell leukemia virus type I (HTLV-I)-associated Mr 52,000 glycoprotein (HA-gp52), which is found on the surface of HTLV-infected cells. Whether HA-gp52 is encoded by the virus or by the infected cells has not yet been established. Using monoclonal HT462 in a competitive binding assay, natural human antibodies specific for HA-gp52 were detected in 97% of the patients from the United States, the Caribbean, and Japan with adult T-cell leukemia but not in healthy donors not exposed to HTLV-I. In contrast, antibodies to HA-gp52 occur in healthy virus-exposed donors, but at a lower prevalence than that observed in patients. Among Japanese from HTLV-I-endemic areas and exposed to the virus as indicated by the presence of antibodies to disrupted HTLV-I, 93% of adult T-cell leukemia patients were also seropositive for HA-gp52 compared to only 16% of healthy individuals. Differing sensitivities in the methods of assaying antibodies to HTLV and HA-gp52 were not responsible for these observations as shown by the lack of correlation of HTLV-I antibody titer with the presence of antibody to HA-gp52. Among adult T-cell leukemia patients, antibody titers to HTLV-I and HA-gp52 also varied independently. These results indicate that HA-gp52 in humans is antigenic and correlated with disease. Detection of antibody to this protein in asymptomatic individuals may be indicative of a predisease condition.