Experimental Glomerulonephritis Induced by Human IgG in Rats

Experimental immune complex glomerulonephritis was induced with human IgG (HIgG) in two strains of rats, Wistar-King-Aptekman (WKA) and spontaneously hypertensive rats (SHR). The rats were pre-immunized s.c. with 1 mg of HIgG in Freund's complete adjuvant, and 8 weeks later were given a daily i.v. 2 mg of HIgG injections for 4 weeks. Renal tissue, obtained at weekly intervals after the beginning of i.v. injections, was examined by light, immunofluorescence and electron microscopic tests. SHR developed an endocapillary proliferative glomerulonephritis with heavy proteinuria after the administration of HIgG for 4 weeks. They had massive depositions of HIgG, rat IgG, and rat C3 both in the mesangial area and along the capillary wall. On the other hand, in WKA rats, the proliferative lesions were scarcely seen and the immune deposits were observed almost exclusively in the mesangium. Moreover, urinary protein excretion of these rats was within normal range. In comparison with bovine serum albumin (BSA) nephritis in SHR, HIgG-induced glomerular lesion was relatively mild. This difference seemed attributable to the nature of the HIgG, such as its molecular weight and immunogenicity.