Identification of Goodpasture target antigens in basement membranes of human glomeruli, lung, and placenta.

Collagenase-digests of human glomerular (GBM), alveolar (ABM), and placenta basement membranes (PBM) were separated by gel filtration columns and the pools rich in Goodpasture antigens (GP) were identified by an antibody inhibition-ELISA. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting on nitrocellulose membranes was performed with each basement membrane preparation. Sera from patients with florid GP-syndrome and antibodies to glomerular basement membrane (anti-GBM antibodies) were incubated with nitrocellulose strips of GBM, ABM, and PBM. Immunoperoxidase staining revealed reactivity with target antigens of 24, 26, 44, and 50 kD in the GBM and of 44 and 50 kD in the ABM and PBM, respectively. No corresponding reactivity was observed using convalescent GP-sera, sera from patients with other immunological diseases or sera from healthy blood donors. The antigens were sensitive to reduction. We conclude, that antigens of similar molecular-weights can be identified by anti-GBM positive sera in human glomerular, alveolar and placenta basement membranes.