ORAL-FEEDING OF RENAL TUBULAR ANTIGEN ABROGATES INTERSTITIAL NEPHRITIS AND RENAL-FAILURE IN BROWN-NORWAY RATS

We have examined whether oral feeding of antigen can regulate the expr ession of autoimmune interstitial nephritis induced by antigen-in-adju vant (RTA/CFA) immunization of Brown Norway rats. Male rats were divid ed into six experimental groups: Group I, RTA/CFA immunization alone; Groups II, III, and IV were pretreated with 1 mg (Group II), 5 mg (Gro up III), and 25 mg (Group IV) of oral tubular antigen every other day for ten days, followed by RTA/CFA immunization; Group V was pretreated with a control antigen, followed by RTA/CFA immunization; and Group V I was immunized with CFA alone. Renal histology, inulin clearance, DTH responses to RTA, and IgG antibody responses to RTA were monitored as endpoints of the study. Our results demonstrated that Group III and I V animals had significantly less severe renal injury, as assessed by i nulin clearance and extent of renal cortical involvement by mononuclea r cells. Group II and TV animals had suppressed DTH responses, and onl y Group IV animals had significantly depressed antigen-specific IgG se rum titers. Group III animals had neither suppressed DTH responses or IgG titers. We conclude that oral administration of tubular antigen ca n modulate the intensity of interstitial nephritis produced by immuniz ation, but that the regulatory mechanism is not dependent (at all dose s of fed antigen) on suppressed DTH reactivity to RTA or suppressed an tigen-specific IgG.