High frequencies of human T-lymphotropic virus type I (HTLV-I) infection and presence of HTLV-II proviral DNA in blood donors with anti-thyroid antibodies

To investigate the relationship between human T-lymphotropic virus (HTLV) types I and II and the pathogenesis of autoimmune thyroid diseases, we examined serum anti-thyroid antibodies in 1019 blood donors with or without serum anti-HTLV-I antibody as well as proviral DNA for HTLV-II in leukocyte DNA by the polymerase chain reaction in 395 blood donors with or without anti-thyroid antibodies. The frequency of donors with anti-HTLV-I antibody who also showed anti-thyroid antibodies (7.9%) tended to be higher than that (6.3%) among donors who did not have the anti-HTLV-I antibody. The frequency of anti-thyroid antibodies in 125 young male donors aged 16–39 years with anti-HTLV-I antibody (4.8%) was significantly higher (P