EXPRESSION OF CYTOKINE MESSENGER-RNA IN LENTIVIRUS-INDUCED ARTHRITIS

Infection of goats with the lentivirus caprine arthritis encephalitis virus (CAEV) leads to persistent infection and development of chronic arthritis. We analyzed the expression of cytokines and viral RNA in th e joints of goats at early time points after experimental infection wi th CAEV and in those of animals suffering from chronic arthritis as a result of natural infection. In situ hybridization experiments showed that the pattern of cytokine expression in caprine arthritis was simil ar to that found in rheumatoid arthritis (RA), with a few cells expres sing the lymphocyte-derived cytokines interferon (IFN)-gamma and inter leukin (IL)-2 and rather more cells expressing monocyte chemoattractan t protein (MCP)-1, IL-6, and tumor necrosis factor (TNF)-alpha. IFN-ga mma mRNA expression in experimentally infected joints peaked at day 12 and was mostly detected in areas containing-viral RNA. At later time points, no IFN-gamma- or virus-expressing cells were found in inflamed joints but both were again detected in goats with severe arthritis, I nterestingly, at the clinical stage of arthritis reflecting the chroni c stage of infection, the inflammatory lesion was found to be immunolo gically compartmentalized. Humoral immune responses and cell-mediated immune responses appeared to concurrently occur in distinct areas of t he synovial membrane.