Experimental autoimmune glomerulonephritis (EAG) induced by homologous and heterologous glomerular basement membrane in two substrains of Wistar-Kyoto rat.

BACKGROUND: Goodpasture's, or antiglomerular basement membrane (GBM), disease presents with rapidly progressive glomerulonephritis, and is caused by auto-immunity to the NC1 domain of the alpha 3 chain of type IV collagen. In order to investigate mechanisms involved in the induction and regulation of glomerulonephritis, experimental models of Goodpasture's disease have been developed in the rat which share many characteristics with the human disease. Induction of experimental autoimmune glomerulonephritis (EAG) involves immunization of susceptible strains with either heterologous or homologous GBM in FCA. However, pathological changes have tended to be mild and/or variable, except in certain protocols using Wistar-Kyoto (WKY) rats.
METHODS: We studied the susceptibility of inbred WKY rats from two different suppliers to the development of EAG. These substrains of rat had different MHC haplotypes (WKY/CR, RT1-1; WKY/Olac, RT1-k), so we proposed that they might show differences in their immune response to GBM antigens. Both substrains were immunized with sheep GBM, pH 7, or rat GBM buffered to pH 3, pH 5 or pH 7.
RESULTS: All immunized rats developed circulating anti-GBM antibodies detectable at 14 days and rising until 28 days, at which time there was linear deposition of IgG on the GBM. WKY/CR rats developed severe focal segmental proliferative and necrotizing glomerulonephritis, with heavy albuminuria, following immunization with rat GBM, pH 7, but only moderate disease following sheep GBM. WKY/Olac rats showed a more variable response, with moderate disease following both rat and sheep GBM. Immunization of either substrain with rat GBM, pH 5, produced a response similar to that with rat GBM, pH 7, but disease was mild following rat GBM, pH 3.
CONCLUSION: EAG in the WKY rat varies in severity according to the substrain of animal and preparation of GBM used for immunization. The model with the most severe and consistent changes was that induced in the WKY/CR rat by rat GBM at pH 7. This model of EAG will be of value for investigating mechanisms of autoimmunity and inflammation in glomerulonephritis, and for attempting novel forms of immunotherapy prior to trials in man.