Different erythrocyte and platelet surface electric charge in various types of glomerulonephritis.

BACKGROUND Some preliminary observations suggest that predisposition to a particular type of glomerulonephritis (GN) may be connected with the genetically determined charge of the glomerular capillary wall. A correlation between erythrocyte surface and the glomerular capillary wall charges has also been observed. The purpose of this study was to verify and extend previous investigations. Therefore we measured erythrocyte and platelet surface charge from patients with idiopathic membranous and mesangial GN as well as idiopathic membranoproliferative GN and lupus nephritis. METHODS The erythrocyte and platelet surface charge was determined by the binding of the cationic dye, alcian blue (AB). A fresh alcoholic AB solution was made for each experiment, which were run in batches of four, each including cells from a healthy person and from patients each with a different type of GN. RESULTS In patients with idiopathic membranous and membranoproliferative GN, a significant decrease in the erythrocyte and platelet charges was observed irrespective of their clinical state (remission or nephrotic syndrome). Erythrocyte charge was decreased despite the normal amount of membranous sialic acid. In contrast, patients with idiopathic mesangial GN, in complete or partial remission, exhibited normal erythrocyte and platelet surface charges. Exclusively in this type of GN, the appearance of nephrotic proteinuria was associated with a slight decrease, the erythrocyte charge, which was not statistically significant (P > 0.1). A reduction in the negative erythrocyte charge in lupus nephritis was less in magnitude than in idiopathic membranous or membranoproliferative GN, and occurred independently of the level of daily proteinuria, whereas the platelet charge was normal. CONCLUSION The decrease of the erythrocyte and platelet charge in idiopathic membranous and mebranoproliferative GN seems to be a pre-morbid feature.