Effect of methylprednisolone and cyclophosphamide in mercury-induced autoimmune glomerulonephritis

The effects of methylprednisolone and of cyclophosphamide were tested in mercury-induced autoimmune disease in Brown-Norway rats. Survival, proteinuria, presence of antiglomerular basement membrane bound antibodies and of immune complex type deposits, amounts of circulating immune complexes, and total serum IgE were studied. Serum IgE represents the most sensitive marker in this drug-induced autoimmune disease. Methylprednisolone alone (1.5 mg/kg per day) affected the course of the disease only slightly. Cyclophosphamide (20 mg/kg every other day) given from day 0 completely prevented all the autoimmune manifestations, but the rats were profoundly immunosuppressed. The same protective effect was obtained with lower cyclophosphamide dosage (15 mg/kg on day 0 and then 2 mg/kg per day). More interestingly, cyclophosphamide given from day 10 or 15 (20 mg/kg twice a week or every other day), at a time when the disease was already expressed, resulted in partial or complete recovery, provided that the rats had not exhibited heavy proteinuria before initiation of treatment. Cyclophosphamide is therefore a powerful agent, able to prevent and even to reduce the consequences of polyclonal activation in this model.