Mesangial glomerulonephropathy with deposition of IgG, IgM, and C3 induced by mercuric chloride: a new model.

A mesangial glomerulonephropathy, characterized by the deposition of rat IgG, IgM, and C3 in the glomerular mesangium, was produced in Wistar rats by a prolonged administration of mercuric chloride (HgCl2). The HgCl2 was dissolved in sterile distilled water (0.2 mg. per ml.), and a group of 15 male Wistar rats was given injections subcutaneously three times a week on alternate days at a dosage of 0.15 mg. per 100 gm. of body weight for 27 weeks. A control group of nine rats was given injections of distilled water only. Mesangial glomerulonephropathy developed in 12 of 15 rats injected with HgCl2 and was characterized by the following: (1) coarse granular and nodular deposition of rat IgG, IgM, and C3 in the mesangium of all glomeruli, (2) absence of staining for rat albumin, IgA, and fibrin, (3) presence of electron-dense deposits in the mesangium, (4) focal and segmental proliferation of the mesangial matrix, (5) interstitial inflammation, (6) tubular atrophy, and (7) deposition of periodic acid-Schiff-positive material in the medulla adjacent to the thin limbs of the loops of Henle. Glycosuria and a slight increase in proteinuria were observed transiently in some rats. The blood urea nitrogen levels were normal in all rats. Eluates from the kidneys with heavy mesangial deposits contained rat IgG. However, the eluted antibody failed to react with normal rat kidney tissue components. None of the above findings were present in the control rats. The study provides a model of a mesangial nephropathy that seems to be immunologically induced; however, the mechanism for the formation and deposition of the immune deposits containing rat IgG, IgM, and C3, and the nature of the antigen(s) have not been elucidated.