IMMUNOHISTOCHEMICAL CHANGES IN SYNOVIAL TISSUE DURING THE COURSE OF ADJUVANT ARTHRITIS

Objective. To study immunohistochemical changes occurring in knee syno vial membranes of rats during the time course of adjuvant arthritis (A A). The effect of treatment with dexamethasone after establishment of arthritis was also studied. Methods. AA was induced in Wistar rats by means of a single injection of a suspension of Mycobacterium butyricum . On Days 7, 14, 17, 21, 28 and 42 after induction, synovial membranes were obtained, frozen and sectioned on a cryostat. Tissue sections we re tested by peroxidase-antiperoxidase method, using the following mon oclonal antibodies: OX19 (CD5), W3/25 (CD4), OX8 (CD8), OX6 (Ia), OX33 (LCA) and OX39 (CD25). Results. Knee synovial membranes obtained from arthritic rats on days of maximum inflammation showed few or no CD5cells, a higher proportion of CD8+ cells, and a higher number of CD4and Ia+ cells than healthy synovial tissues. CD25+ cells were observed from Day 7 postinduction and remained numerous throughout the study. Conclusion. Few T lymphocytes (CD5+) were found in arthritic synovial membrane, whereas an increase of cells expressing CD8, CD4, CD25, Ia, and LCA was found. These increases (except CD8) are not evident in dex amethasone treated rats.