Antibody against human immunodeficiency virus type 1 (HIV-1) Tat protein may have influenced the progression of AIDS in HIV-1-infected hemophiliac patients.

Retrospective analysis of serum samples from a group of hemophiliac patients who became infected with human immunodeficiency virus type 1 (HIV-1) between 1984 and 1985 has shown that, at variance with other HIV-1-infected patients, at the onset, or at least at a very early phase of HIV-1 infection, they constantly have elevated levels of antibodies against HIV-1-transactivating Tat protein and an absent or barely detectable p24 antigenemia. Anti-Tat antibodies in initial serum samples from hemophiliac patients were probably the consequence of the passive administration of immunoglobulins present in low- or intermediate-purity clotting factor concentrates prepared from HIV-1-infected blood. Furthermore, the analysis of serial serum samples obtained during the course of the disease, in which passively acquired anti-Tat antibodies were substituted by actively produced antibodies, demonstrated an inverse relationship between anti-Tat antibody and p24 anti-genemia levels throughout the observation period. These data seem to suggest that anti-Tat antibody may have some influence on the course of HIV-1 infection.