Increased mast cell density in renal interstitium is correlated with relative interstitial volume, serum creatinine and urea especially in diabetic nephropathy but also in primary glomerulonephritis.

In primary glomerulonephritis the degree of interstitial fibrosis governs the renal function. Mast cells participate in renal interstitial fibrosis, but its role remains poorly understood. Some of human mast cells contain chymase and chymase may participate in local angiotensin formation. Material consisted of 35 renal biopsies. The diagnoses included diabetic nephropathy, mesangial glomerulopathy, IgA glomerulopathy and membranous glomerulopathy. Chymase and tryptase-positive cells were stained by immunohistochemistry and counted. Relative interstitial volume (RIV) was measured by point counting method. The density of tryptase-positive cells was 5.26 per 10 high power fields; the density of chymase-positive cells was 2.72. The counts were higher than in controls and highest in diabetic nephropathy. Creatinine serum level was related to density of chymase-positive cells (R = 0.57), density of tryptase-positive cells (R = 0.59) and RIV (R = 0.77). On multiple regression analysis creatinine level was influenced by RIV but also by density of chymase-positive cells. Our findings indicate that both types of mast cells are present in renal interstitium in diabetes and glomerulonephritis, and may influence the renal function. Chymase-positive cells may be more important in this regard.