Arthritis in patients infected with human T lymphotropic virus type I. Clinical and immunopathologic features

Ten patients with chronic inflammatory arthropathy and the human T lymphotropic virus type I (HTLV‐I) are described. These patients showed chronic persistent oligoarthritis, associated with proliferative synovitis, in large joints. The place of birth or residence of these patients was within the area endemic for adult T cell leukemia (ATL) and HTLV‐I. The age at onset of articular symptoms tended to be higher in these patients than in typical rheumatoid arthritis patients. Anti–HTLV‐I antibodies were detected in both sera and synovial fluids from all patients. Western blot analysis revealed antibodies to viral gag proteins (p19, p24, and p28). Atypical lymphocytes with nuclear indentations, consistent with ATL‐like cells, were observed in both synovial fluid and synovial tissue. Furthermore, HTLV‐I proviral DNA was integrated into the DNA of synovial fluid cells and synovial tissue cells. These findings suggest that HTLV‐I might be involved in the pathogenesis of this unique arthropathy.