Autoimmune disease induced by oral administration of mercuric chloride in Brown-Norway rats

Only few reports are available on the consequences of chronic oral administration of low doses of mercuric chloride (HgCl2). Forty Brown-Norway rats received 150 micrograms HgCl2/100 g body weight 3 times a week by gavage or by i.m. injection with 100 micrograms twice per week. After 2 weeks of oral HgCl2 administration, the rats lost weight and hair. Phases of proteinuria were observed in weeks 5-8 and then continuously from week 12 until the end of the experiment at week 39. Antibodies binding to renal, intestinal, and vascular basement membrane developed after 2 weeks; circulating immune complexes were detectable in increasing titers starting at week 3. There were linear deposits of IgG, IgM, and IgA in the glomerular basement membrane and tubular basement membrane, and along the intestinal basement membrane. After week 11, the first granular immune deposits were observed in renal and intestinal basement membranes. Light microscopy showed thickening of glomerular basement membrane, mesangial matrix, and tubular basement membrane. In addition, interstitial nephritis was observed in some animals. Interestingly, kidney involvement was as severe in the orally as the i.m.-treated animals.