QUANTITATIVE-ANALYSIS OF IMMUNOHISTOLOGICAL CHANGES IN THE SYNOVIAL-MEMBRANE OF SHEEP INFECTED WITH MAEDI-VISNA VIRUS

We have carried out a quantitative immunohistological analysis of syno vial membrane from the joints of clinically arthritic sheep naturally infected with Maedi-Visna virus (MVV) and compared the results to subc linically affected joints (carpal and tarsal) from infected sheep and to joints from a control population. Significantly elevated numbers of all three T lymphocyte subsets (CD4+, CD8+ and gamma delta) were foun d in the synovia from clinically arthritic sheep compared to controls. There was also a significant increase in the number of CD8+ T lymphoc ytes in the carpal synovium of subclinically arthritic animals. In bot h clinically arthritic and subclinical disease states CD8+ T cells pre dominated over CD4+ T cells and T cells bearing the gamma delta T cell receptor. Significant increases were also observed in the numbers of cells staining for MHC class II antigens in the synovial lining cell l ayer and subintimal cell populations of synovia from clinically arthri tic sheep. These increases were apparent in the subintimal cell popula tion at the subclinical stage of disease. Macrophage-like cells staini ng for the viral core protein p15 were observed in some of the most in flamed samples. The data are thus consistent with a disease process dr iven by chronic viral antigen presentation to infiltrating T cells, an d could serve as a model for elucidating the mechanisms underlying som e types of inflammatory joint disease in man. (C) 1994 Academic Press, Inc.