Arthritis in rhesus monkeys experimentally infected with simian immunodeficiency virus (SIV/DELTA)

The joint tissues from 36 rhesus (age 2-5 years) infected with SIV/Delta were graded into four groups and then correlated with the following systemic immunologic parameters: numbers of CD4+, CD4+ plus CD29+, and CD20+ cells and SIV/Delta antigenemia. Grade I (n = 16) consisted of normal synovial membrane; grade II (n = 8) consisted of synovial hyperplasia; grade III (n = 8) consisted of a mononuclear cell infiltrate, and grade IV (n = 4) consisted of synovial membrane infiltration of syncytial cell and mononuclear type cells. Synovial membranes from 20 uninfected age-matched rhesus were compared with infected animals and were graded 1. Immunostaining of the tissue phase lymphocytes and viral antigen was performed using monoclonal antibodies commercially available and a monoclonal antibody produced against a core protein of the SIV/Delta agent. SIV/Delta infection resulted in a reduction in cells doubly stained for CD4+ and CD29+ and a relative increase in CD8+ stained cells. A significant (ANOVA) difference was not observed in CD4+, CD4+ plus CD29+, CD8+, or CD20+ among the various grades of arthritis. Viral antigen was demonstrated in syncytial cells of the grade IV reaction. This finding suggests that the SIV/Delta arthritis is a primary viral reaction.