IMMUNOHISTOLOGY OF THE EARLY COURSE OF LENTIVIRUS-INDUCED ARTHRITIS

Caprine arthritis encephalitis (CAE) is a lentiviral infection of goat s characterized by mononuclear cell infiltration of various tissues, m ost prominently the joints, mammary glands and, in young animals, the brain. We have investigated the early stages of arthritis induced by i ntracarpal and intravenous infection with molecularly cloned CAE virus . Analysis of the synovial membranes by immunohistological methods sho wed that the proportion of CD8(+) T cells peaked around day 12 post-in fection. CD4(+) T cells increased to a lesser degree. The relative pro portion of B cells rose steadily post-infection. At 33 days post-infec tion, plasma cells accounted for over one third of all inflammatory ce lls in the inflamed synovium. Histopathologically, the arthritic lesio ns in the synovial membranes closely resembled those in membranes of a nimals with a 2-year history of chronic arthritis. Our observations in dicate that this type of short-term experimental infection is particul arly suitable for studying the pathogenesis of goat lentiviral infecti on. In addition, our observations support the view that a predominantl y humoral (type 2) immune response may contribute to the pathogenesis of CAE.