Glomerular Detection of Schistosomal Antigen by Immunoelectron Microscopy in Human Mansonian Schistosomiasis

Abstract

Schistosomal antigens (S. mansoni) were detected in glomeruli of nine patients with nephropathy and nephrotic syndrome by immunoelectron microscopy. The criteria for patients' selection were presence of intestinal schistosomiasis and absence of any surgical or other medical diseases, particularly lupus erythematosus, syphilis, and hepatitis B and C, which could explain the renal disease. When examined by light microscopy, kidney biopsies showed type I membranoproliferative glomerulonephritis in four patients, focal segmental glomerulosclerosis in two, and mesangioproliferative glomerulonephritis, membranous glomerulonephritis, and minimal change disease in one each of the remaining three patients. Immunofluorescence showed mainly immunoglobulin G (IgG), IgM, and different complement components (C3, Clq) deposits, particularly in the mesangial area, in eight patients. All patients had gold-labeled schistosomal antigen deposits in their glomeruli, chiefly in mesangial cells and matrix, along the glomerular membrane, and occasionally in the cytoplasm of epithelial cells. Although membranous glomerulonephritis has been rarely described in association with schistosomiasis and minimal change disease may be occasionally caused by an infectious disease like syphilis, the absence of definite experimental models and epidemiologic data suggests that coincidental pathologies without causal relationship with schistosomiasis cannot be ruled out to explain these findings.