Background:Morphometric investigations were performed to determine whether mast cells correlate with tubulointerstitial fibrosis in acute renal transplant rejection (ARTR) and to examine the relationship between mast cells, interstitial a-smooth muscle actin (α-SMA) expression, and interstitial infiltrates.Material/Methods: Twenty-four renal allograft biopsy specimens from patients with ARTR were examined quantitatively by means of a computer image analysis system. As a control 11 allograft biopsy specimens were used from patients with no signs of rejection.Results: The morphometric study revealed that the mean values of the interstitial tryptase positive cells, expression of α-SMA, interstitial volume, CD 68+, CD 43+ and CD 20+ cells were significantly increased in ARTR patients in comparison to controls. In the ARTR group there were significant positive correlations between interstitial tryptase positive cells and interstitial expression of α-SMA, interstitial volume, CD 43+ and CD 68+. Moreover, CD 68 positive cells significantly correlated with interstitial volume (r=0.51, p<0.02). The correlations between interstitial tryptase positive cells and CD 20+ cells as well as between CD 43+ and CD 20+ cells and interstitial volume were positive, but did not reach statistical significance.
Conclusions: Our findings demonstrate that mast cells are one of the constitutive cell types in the interstitium in ARTR. Although the significant positive correlations between interstitial mast cell count and relative interstitial volume, as well as interstitial expression of a-SMA, suggest that these cells have a role in the development of early interstitial fibrosis in renal allografts, these relationships need further investigation.

Keywords: Antibodies, Monoclonal - chemistry, Antigens, CD - biosynthesis, Antigens, CD20 - biosynthesis, Antigens, CD43, Antigens, Differentiation, Myelomonocytic - biosynthesis, Fibrosis, Graft Rejection, Image Processing, Computer-Assisted, Immunophenotyping, Immunosuppressive Agents - pharmacology, Kidney - pathology, Kidney Transplantation - methods, Mast Cells - pathology, Microscopy, Electron, Microscopy, Fluorescence, Muscle, Smooth - metabolism, Sialoglycoproteins - biosynthesis, Software, Antibodies, Monoclonal - chemistry, Antigens, CD - biosynthesis, Antigens, CD20 - biosynthesis, Antigens, CD43, Antigens, Differentiation, Myelomonocytic - biosynthesis, Fibrosis, Graft Rejection, Image Processing, Computer-Assisted, Immunophenotyping, Immunosuppressive Agents - pharmacology, Kidney - pathology, Kidney Transplantation - methods, Mast Cells - pathology, Microscopy, Electron, Microscopy, Fluorescence, Muscle, Smooth - metabolism, Sialoglycoproteins - biosynthesis, Software