Alternative routes of immunization for the induction of experimental autoimmune uveoretinitis (EAU) in rodents: a comparison

Experimental autoimmune uveoretinitis (EAU) in rodents is a widely used model of ocular autoimmunity. EAU has traditionally been elicited by injecting the uveitogenic protein in complete Freund's adjuvant (CFA) into the footpad(s) (FP). Because this route of immunization causes severe arthritis and inflammation, it is being banned by many institutions and investigators are switching to the subcutaneous (SC) route. However, there are no studies that systematically compare the outcome of these two immunization routes using defined clinical, histopathological and immunological criteria. We therefore undertook to compare the FP and SC routes of immunization in the Lewis rat and in the B 10. A mouse models of EAU. Animals were immunized with interphotoreceptor retinoid-binding protein (IRBP) or the retinal soluble antigen (S-Ag) in CFA, either by the traditional FP route or by the SC route. The parameters studied were kinetics and severity of EAU by clinical observation and by histopathology, respectively, as well as immunological responses by delayed-type hypersensitivity (DTH), serum antibody titers and lymphocyte proliferation to the uveitogen. In mice immunized with graded doses of IRBP, development of disease induced by the FP and SC methods had essentially identical kinetics. However, the SC method resulted in a somewhat higher incidence and severity of disease as well as higher DTH at the lower antigen doses. Antibody titers tended to be higher with FP immunization. In rats immunized with S-Ag, kinetics and severity of disease, DTH, proliferative responses of draining lymph node cells to the immunizing antigen, and serum antibody titers induced by FP and SC methods were similar. In rats immunized with IRBP, SC immunization resulted in somewhat higher responses across the board than FP. We conclude that at higher doses of antigen disease scores and immunological responses in animals immunized SC are comparable to those of FP-immunized animals. At limiting doses of antigen, however, the SC route appears to result in more severe disease than the traditional FP method.