[HTLV-I infection in primary Sjögren's syndrome--epidemiological, clinical and virological studies].

The HTLV-I seroprevalence rate among the patients with Sjögren's syndrome (SjS, 23.0%) was significantly higher than that among blood donors (3.4%). The age-adjusted summary odds ratio of HTLV-I infection among SjS patients as compared with blood donors was 3.1. The etiologic fraction, i.e., the proportion of SjS in the study population that are attributable to HTLV-I infection, was estimated to be 17.6%. Titers of serum antibodies to HTLV-I in the seropositive SjS patients were significantly higher than those among healthy carriers. IgM class antibodies were commonly detected in sera of SjS patients. Salivary IgA class antibodies were common among seropositive SjS patients, but not in HAM patients or in healthy subjects. The findings strongly suggest that HTLV-I is involved in the pathogenesis of the disease in a subset of patients with SjS in endemic areas.