Plasma exchange in the treatment of mesangiocapillary glomerulonephritis.

9 patients with primary glomerulopathies and slowly progressive renal failure were treated by regular plasma exchanges without immunosuppressive drug therapy. All 3 patients with the subendothelial type of mesangiocapillary glomerulonephritis (MCGN-I) had no progression of their renal failure while undergoing plasma exchanges. The creatinine rose when treatment was stopped and fell again in 2 patients who restarted plasma exchange. 2 patients with hypocomplementaemia and dense deposit disease (MCGN-II) and all 3 patients with idiopathic membranous nephropathy (IMN) did not benefit. 1 patient with normo-complementaemic MCGN-II had some improvement in renal function which lasted 18 months. Proteinuria fell or was unchanged during the 1st month of plasma exchange in the 4 who improved and increased in the 5 who did not. The response to plasma exchanges could not be attributed to removal of circulatory complexes or changes in reticulo-endothelial function. Regular 2.8-litre plasma exchanges using 4.3% immunoalbumin proved to be safe for periods up to 44 months. Regular plasma exchange appears to prevent progression to renal failure in patients with MCGN-I.