Analysis of prognostic predictors in idiopathic membranous nephropathy

We studied clinical and histologic parameters at the time of renal biopsy of 19 patients with idiopathic membranous nephropathy (IMN) to investigate the predictors for prognosis of IMN. Nineteen patients diagnosed by open renal biopsy between 1988 and 1993 and followed for at least 5 years were divided into two groups according to the latest follow-up renal function. Group I included 16 patients with normal renal function at the last follow-up point. Group II included three patients with end-stage renal failure at the last follow-up point. Antibodies to CD68, CD45RO, alpha-SMA, collagen IV, and collagen VI were used to investigate glomerular and interstitial changes in biopsy specimens by the indirect enzyme-labeled antibody method. Degree of global glomerulosclerosis, segmental glomerulosclerosis, adhesion to Bowman's capsule, and crescent formation were evaluated by light microscopy (periodic acid-Schiff, periodic acid-metheramine [PAM] staining). The difference between the two groups was analyzed by Mann-Whitney U: test. The number of interstitial cells, the number of interstitial CD45RO-positive cells, and increases of interstitial collagen IV and VI were found to be the most important factors for prognosis of IMN. These findings suggest that the extent of tubulointerstitial changes (cellular infiltration and fibrosis) determines the prognosis of renal function in IMN.