Sera from patients with poststreptococcal glomerulonephritis (PSGN) known to have antibodies to proteoglycans were studied for the presence of antibodies against other basement membrane (BM) components. BM collagen (type IV) was isolated in the native state by extracting bovine anterior lens capsule (ALC) with 0.5 M acetic acid. The 7-S (collagenous) domain and the NC-1 (noncollagenous) domain of type IV collagen were obtained after bacterial collagenase digestion of ALC followed by gel filtration. Laminin was isolated from the mouse EHS tumor and fibronectin from human plasma. Immunologic studies, using an ELISA and electroimmunoblot, revealed the presence of antibodies that reacted with intact, native type IV collagen and the 7-S collagenous domain of this molecule. Reaction with the NC-1 (noncollagenous) domain was minimal, and not higher than that obtained with control sera. Laminin reaction strongly with the patients' sera, but fibronectin did not. Unlike sera from patients with Goodpasture syndrome, which contain antibodies primarily against the NC-1 (noncollagenous) domain of type IV collagen, sera from patients with acute PSGN contain antibodies against all the major macromolecular components of BM. This difference in immunologic reactivity may account for the observed differences in the pathologic picture at the glomerular level.

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