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.