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* Department of Medicine, University of New South Wales and Liverpool Hospital and
Anatomical Pathology, South West Sydney Area Pathology Service, Liverpool, New South Wales, Australia; and
Department of Renal Medicine, St. Vincents Hospital, Fitzroy, Victoria, Australia
Passive Heymann nephritis (PHN), a model of human membranous nephritis, is induced in susceptible rat strains by injection of heterologous antisera to rat renal tubular Ag extract. PHN is currently considered the archetypal complement-dependent form of nephritis, with the proteinuria resulting from sublytic glomerular epithelial cell injury induced by the complement membrane attack complex (MAC) of C5b-9. This study examined whether C6 and MAC are essential to the development of proteinuria in PHN by comparing the effect of injection of anti-Fx1A antisera into PVG rats deficient in C6 (PVG/C6) and normal PVG rats (PVG/c). PVG/c and PVG/C6 rats developed similar levels of proteinuria at 3, 7, 14, and 28 days following injection of antisera. Isolated whole glomeruli showed similar deposition of rat Ig and C3 staining in PVG/c and PVG/C6 rats. C9 deposition was abundant in PVG/c but was not detected in PVG/C6 glomeruli, indicating C5b-9/MAC had not formed in PVG/C6 rats. There was also no difference in the glomerular cellular infiltrate of T cells and macrophages nor the size of glomerular basement membrane deposits measured on electron micrographs. To examine whether T cells effect injury, rats were depleted of CD8+ T cells which did not affect proteinuria in the early heterologous phase but prevented the increase in proteinuria associated with the later autologous phase. These studies showed proteinuria in PHN occurs without MAC and that other mechanisms, such as immune complex size, early complement components, CD4+ and CD8+ T cells, disrupt glomerular integrity and lead to proteinuria.
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1 This work was supported by the National Health and Medical Research Council (NH&MRC) of Australia, Australian Kidney Foundation, the South Western Sydney Area Health Service, and Ingham Research Foundation. S.T.S. was an NH&MRC PhD Scholar.
2 Address correspondence and reprint requests to Dr. S. Timothy Spicer, Renal Unit, Liverpool Health Service, Locked Bag 7090 s, Liverpool BC 1871, New South Wales, Australia. E-mail address: spicerst{at}exemail.com.au
3 Abbreviations used in this paper: HN, active Heymann nephritis; PHN, passive Heymann nephritis; GBM, glomerular basement membrane; GEC, glomerular epithelial cell; MAC, membrane attack complex; ATx, adult thymectomy; EAE, experimental autoimmune encephalomyelitis; EM, electron microscopy.
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