ACTIVATED IMMUNOCOMPETENT CELLS IN RAT COLITIS MUCOSA INDUCED BY DEXTRAN SULFATE SODIUM AND NOT COMPLETE BUT PARTIAL SUPPRESSION OF COLITISBY FK506

Administration of dextran sulfate sodium (DSS) solutions to rats induc ed colitis which resembled mucosal lesions of human ulcerative colitis . Recent reports have shown that some cytokines are related to the pat hogenesis of ulcerative colitis. In the present report, we describe th e production of two cytokines in colitis mucosa in this DSS model. Usi ng a cytotoxicity assay and a radioimmunoassay, we observed significan t increases in levels of tumor necrosis factor-alpha (TNF-alpha) in th e colitis mucosa and detected interleukin-1 alpha in the mucosa of 3 o f 5 DSS rats and an increase in TNF-alpha had a tendency to be inhibit ed by treatment with FK506. Immunohistochemical investigation of DSS m ucosa showed that the number of activated T cells increased at the ear lier phase of inflammation. Luminol-dependent chemiluminescence values and myeloperoxidase activities were increased in the late phase of co litis and were suppressed by the FK506 treatment. These findings may s upport the role of TNF-alpha and T-cell activation in the pathogenesis of DSS colitis.