Autoimmune glomerulonephritis induced by mercury vapour exposure in the Brown Norway rat

Subcutaneous injections of mercuric chloride induce an autoimmune glomerulonephritis with both granular and linear IgG deposits along the glomerular capillary wall and proteinuria. This disease is due to a T cell dependent polyclonal B cell activation responsible for production of antibodies against self (glomerular basement membrane, immunoglobulins, DNA, myeloperoxydase) and non self (sheep red blood cells, trinitrophenol (TNP)) components. Increase in serum IgE concentration is the hallmark of this disease. To determine if mercury vapours have pathogenic effects is an important problem of public health. The aim of this study was, first to compare the effects of mercury vapour exposure to those of mercury injections and, second, to compare the effects of high doses to those of low doses of mercury. Two exposure levels were studied corresponding to a mercury absorption of 13.1 mumol/week per kg body wt. and 1.7 mumol/week per kg body wt. during a 5-week period. It will be shown that, whereas the mercury concentration in the kidneys was similar in injected--and vapour exposed--rats, the mercury concentration in blood at the end of the exposure was about twice as high in the injected animals. Blood concentration of mercury was related to dose level but kidney content of mercury was similar in all groups, in spite of a dose difference by a factor of seven between low and high exposure. Mercury vapour and HgCl2 injections both trigger autoimmunity to the same extent and, in both cases the extent of autoimmune manifestations was dose-dependent.