Significance of activated mast cells in submucosa and muscularis propria of patients with Crohn's disease detected by a novel antimast cell surface molecule antibody

Abstract

SummaryBackgroundDegranulated mast cells may be missed by histochemical and immunohistological techniques, making the histological assessment of activated mast cells difficult.AimTo use a novel mast cell surface antigen 1 (MASA‐1) to detect activated mast cells.MethodsSurgical samples of human intestine were obtained from 15 patients with ulcerative colitis (UC), 14 patients with Crohn's disease (CD) and 11 controls. Frozen sections were cut and MASA‐1 was detected and quantified by enzyme immunohistology. Immunohistological double staining with anti‐MASA‐1 and either anti‐CD68 or anti‐c‐Kit antibody was also performed.ResultsThe number of MASA‐1‐positive cells was significantly higher in the submucosal layer and muscularis propria in patients with CD than in patients with UC or controls. The number of MASA‐1‐positive cells was significantly higher in the muscularis propria in patients with UC in highly inflamed colon compared with controls and less inflamed colon. Human intestinal MASA‐1‐positive cells are not from the macrophage lineage and showed heterogeneous expression of c‐Kit.ConclusionThe increased number of mast cells in the submucosa and muscularis propria in patients with CD suggests that the involvement of activated mast cells in transmural inflammatory responses possibly including tissue remodelling.