Experimental Goodpasture's syndrome in Wistar-Kyoto rats immunized with α3 chain of type IV collagen

Background. Glomerulonephritis and lung hemorrhage of autoimmune Goodpasture syndrome develop due to immune reactions against epitope(s) of the non-collagenous (NC1) domain of alpha 3-chain of type IV collagen [alpha 3(IV) NC1]. Whether thymic mechanisms have a role in the loss of tolerance to the Goodpasture epitope has not been established. We studied the renal and pulmonary effects of immunization with different forms (monomer, dimer, or hexamer) of alpha 3(IV) NC1 collagen in Wistar-Kyoto (WKY) rats: and assessed whether the intrathymic inoculation of the antigen may protect against anti-GEM disease. Methods. WKY rats were immunized with bovine alpha 3(IV) monomer. dimer, or hexamer, or with alpha 3(IV) NC1 synthetic peptide. Renal function: kidney and lung immunohistology, and circulating and tissue bound antibodies to type IV collagen chains were analyzed. Effects of intrathymic inoculation of antigen on subsequent disease induction were analyzed in WKY rats given alpha 3(IV) NC1 dimer or GEM preparation intrathymically 48 hours before immunization. Results. Proteinuria, linear IgG deposition in GEM, and crescentic glomerulonephritis developed in WKY rats immunized with alpha 3(IV) NC1 dimer or hexamer. Lesions were dose-dependent upon injections of 10 to 100 mu g dimer. The alpha 3(IV) NC1 monomer induced less severe proteinuria and no crescents. Pulmonary hemorrhage was detectable in 35% of rats immunized with 25 to 100 mu g alpha 3(IV) NC1 dimer; alpha 3(IV) synthetic peptide (36 carboxyl terminal) did not induce disease. Rats injected intrathymically with up to 100 mu g alpha 3(IV) NC1 dimer or with GEM 48 hours before immunization were not protected against subsequent development of proteinuria and glomerulonephritis. Conclusions. These findings document that glomerulonephritis and lung hemorrhage can be elicited in WKY rats by immunization with alpha 3(IV) NC1. Failure of the intrathymic inoculation of antigen to prevent disease suggests that immunological tolerance cannot be achieved by this intervention, in contrast to other autoimmune conditions, and may imply independent roles for cellular and humoral nephritogenic pathways in anti-GBM nephritis.