HIGH SEROPREVALENCE OF ANTI-HTLV-I ANTIBODY IN RHEUMATOID-ARTHRITIS

Objective. To investigate the association between human T lymphotropic virus type I(HTLV-I) infection and rheumatoid arthritis (RA) in Nagas aki, an area highly endemic for HTLV-I infection. Methods. Sera from 1 13 female patients with RA and 19,796 female blood donors were screene d for anti-HTLV-I antibodies with a gelatin particle agglutination kit and confirmed using an immunoblotting kits. Results. The age-adjusted summary odds ratio of HTLV-I infection among RA patients, as compared with blood donors, was 2.8 (95% confidence interval [95% CI] 1.8-4.6) . The etiologic fraction, i.e., the proportion of RA in the study popu lation that is attributable to HTLV-I infection, was estimated to be 1 3.2% (95% CI 5.1-21.2). There was no significant difference in the cli nical and laboratory findings between HTLV-I-infected and HTLV-I-uninf ected RA patients. Conclusion. These epidemiologic findings support th e idea that HTLV-I infection is a risk factor for RA, and suggest that similar to 13% of the cases of RA in females living in Nagasaki are a ssociated with HTLV-I infection.