Figure 3

(a) Histopathological features and (b) immunohistochemical expression of Tax protein in synovial tissue obtained from a representative human T lymphotropic virus type I (HTLV-I) carrier with osteoarthritis (case 6). The synovium showed focal papillary proliferation together with hyperaemic dilated vessels and mild lymphocytic infiltration. Unlike in rheumatoid arthritis, however, neither stratified synovial lining cells nor lymphoid follicle formation were evident throughout the whole tissue. Tax-positive synoviocytes could be sparsely observed in the papillary projected area of the synovium. Scale bar, 100 μm.