Electrical charge. Its role in the pathogenesis and prevention of experimental membranous nephropathy in the rabbit

• Published in: The Journal of clinical investigation 1983-03, Vol.71 (3), p.487-499
• Main Authors: Adler, S G, Wang, H, Ward, H J, Cohen, A H, Border, W A
• Format: Article
• Language: English
• Subjects: Animals; Antigen-Antibody Complex; Antigens - isolation & purification; Basement Membrane - immunology; Binding Sites - drug effects; Cations; Disease Models, Animal; Electrolytes - metabolism; Glomerulonephritis - etiology; Glomerulonephritis - immunology; Glomerulonephritis - metabolism; Kidney - ultrastructure; Male; Protamines - pharmacology; Rabbits; Serum Albumin, Bovine - administration & dosage
• ISSN: 0021-9738
• DOI: 10.1172/jci110793

Intravenous cationic bovine serum albumin (BSA, pI > 9.5) induces membranous nephropathy in immunized rabbits. In this study, unimmunized rabbits received intravenous injections of cationic (n = 3) or native (n = 3) or native (n = 3) BSA, followed by ex vivo isolated left renal perfusions with sheep anti-BSA antibody. Capillary wall deposits of IgG and C3 were seen exclusively in the group receiving cationic BSA, confirming an in situ pathogenesis for cationic, BSA-induced membranous nephropathy, and demonstrating the importance of a cationic antigen for its production. We then explored whether membranous nephropathy in this model is prevented by the concomitant injection of protamine sulfate, a filterable, relatively non-immunogenic polycation. An in vitro study demonstrated that protamine sulfate incubated with glomerular basement membrane (GBM) decreased the subsequent binding of radiolabeled cationic BSA (P < 0.05). In vivo, protamine sulfate was shown to bind to anionic sites in the glomerular capillary wall after intravenous injection.Groups of rabbits received 3 wk of daily intravenous injections of cationic BSA alone (n = 15) or cationic BSA and protamine (n = 18). After 2 wk of injection of cationic BSA alone, typical membranous nephropathy developed. Granular deposits of IgG and C3 were present along the GBM associated with subepithelial dense deposits, foot process effacement, and marked albuminuria. Protamine significantly reduced or prevented the formation of deposits (P < 0.001) and in6 of 18 protamine-treated animals, existing deposits decreased or disappeared between 2 and 3 wk of injection. Albuminuria was significantly reduced in protamine-treated animals with a mean of 124+/-55 mg/24 h compared to 632+/-150 mg/24 h in the control group receiving cationic BSA alone. No significant differences between the groups were noted in serum lev9lsof IgG, C3, anti-BSA antibody, or circulating immune complex size. Studies in additional animals (n = 5) given radiolabeled cationic BSA showed that protamine did not alter the clearance of cationic BSA from serum. Control experiments showed that protamine's beneficial effects were not related to its weak anticoagulant property or toits theoretical ability to deplete tissue histamine. The administration of heparin (n = 6) or diphenhydramine (n = 6) had no effect on the development of the epimembranous lesion compared to the group receiving cationic BSA alone. In addition, homogenized whole kidney histamine