Inflammatory arthritic process, iridocyclitis and immune response to articular and ocular antigens in Wistar rats injected with T-gondii trophozoites

The present study deals with the potential role of T gondii in inducing an arthritic inflammatory process. Wistar rats were injected subcutaneously (s c) into the right footpad with viable T. gondii trophozoites emulsified in incomplete Freund's adjuvant (IFA). The control group was injected with IFA . All parasite-injected animals developed a local inflammatory process char acterized by hind limb swelling and marked restriction of ankle motility ap proximately 25 days after injection. Histopathological studies of the joint s, carried out 90 days after injection, revealed intense mononuclear infilt ration, proliferation of granulation tissue, giant cells and necrosis in th e synovia of 90% of T. gondii-injected rats. Strikingly, 40% (4/10) of the parasite-injected animals developed iridocyclitis, which was characterized by intense mononuclear infiltration around the iris-ciliary microvasculatur e in two animals and a slightly pronounced infiltrate of polymorphonuclear and mononuclear cells in two other animals. Antibodies to soluble T. gondii antigens (STAg) were detected in all parasite-injected rats. Antibodies ag ainst articular and ocular antigens such as proteoglycans, type II collagen , retinal S antigen and iris antigens were detected by ELISA in 40, 80, 70 and 70% of T. gondii-injected animals, respectively. Control animals inject ed with IFA failed to develop any articular or ocular process or humoral im mune response. The present study demonstrated that footpad sc injection of Wistar rats with viable T. gondii trophozoites was able to induce a localiz ed inflammatory arthritic process which, in some of the animals, was accomp anied by iridocyclitis and immune response against articular and ocular com ponents. (C) 1999 Academic Press.