Quantitative analysis of the interstitial mast cells in idiopathic mesangiocapillary glomerulonephritis type I.

Fourteen renal biopsy specimens from patients with mesangiocapillary glomerulonephritis type I (MCGN-I) for whom both light and electron microscopy as well as immunofluorescence microscopy and full clinical data were available were examined quantitatively. As a control 10 biopsy specimens of kidneys removed because of trauma were used. Morphometric investigations were performed by means of a computer image analysis system to evaluate whether mast cells have a role in tubulointerstitial fibrosis in MCGN-I and to examine the relationship between mast cells and interstitial alpha-smooth muscle actin (alpha-SMA) expression as well as interstitial infiltrates. The morphometric study revealed that the mean values of the interstitial tryptase positive cells, expression of alpha-SMA, interstitial volume, CD 68+, CD 45RB+, CD 43+ and CD 20+ cells were significantly increased in MCGN-I patients in comparison with control group. In MCGN-I group there were significant positive correlations between interstitial tryptase positive cells and interstitial expression of alpha-SMA, interstitial volume, serum creatinine as well as CD 43+ and CD 68+ cells. The correlations between interstitial tryptase positive cells and CD 45+, as well as CD 20+ cells did not reach statistical significance. In conclusion, our findings demonstrate that mast cells are one of the constitutive cell types in the interstitium in MCGN-I. Additionally, significant positive correlations between interstitial mast cell count and relative interstitial volume as well as serum creatinine concentration suggest the role of these cells in the development of interstitial fibrosis which may contribute to the renal deterioration in patients with MCGN-I.