Quantitative analysis of interstitial mast cells in lupus and non-lupus membranous glomerulopathy

Eleven renal biopsy specimens from patients with lupus membranous glomerulopathy (LMGN) and 16 from patients with primary (nonlupus) membranous glomerulopathy (NLMGN) for whom light, electron microscopy and immunofluorescence microscopy, and full clinical data were available were examined quantitatively. As a control 10 biopsy specimens of the 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 lupus and nonlupus membranous glomerulopathy 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 interstitial tryptase positive cells, expression of alpha-SMA, interstitial volume, CD68+, CD45RB+, CD43+ and CD20+ cells were significantly increased in LMGN as compared with NLMGN. In both LMGN and NLMGN groups there were significant positive correlations between interstitial tryptase positive cells and interstitial expression of alpha-SMA, interstitial volume, serum creatinine as well as CD68+ cells. The present data suggest that in cases of membranous glomerulopathy with a large number of interstitial mast cells systemic lupus erythematosus should be taken into consideration, even if this aetiology was not clinically suggested at the time of biopsy. Additionally, in both LMGN and NLMGN significant positive correlations between interstitial mast cell count and relative interstitial volume support the role of these cells in the development of interstitial fibrosis, however this relationship needs further investigations.