Mast cells and inflammatory mediators in chronic ulcerative colitis

Chronic ulcerative colitis (CUC) is an inflammatory destructive disease of the large intestine characterized by motility and secretion disorders. In the past decade, attention has been paid to the role of neuronal structures and mast cells in regulating inflammatory and immune responses in inflammatory bowel disease (IBD). The present study was performed to demonstrate neuronal fibres (NF) and cells containing substance P (SP), tryptase and serotonin (SER) in the colonic wall of patients with CUC in remission. Biopsy specimens of 6 patients with CUC were investigated with immunocytochemical methods. Normal colon tissue obtained from 6 patients with rectal carcinoma was used as a control. An increased number of SP- and SER-positive NF was found in all the layers of the intestinal wall. The number of SER-containing endocrine cells in the mucosal glands was also increased per crypt. Tryptase-, SP- and SER-immunopositive mast cells were found in higher amounts than in control specimens in close apposition to the basal lamina of the glands among the epithelial cells and in other layers of the gut wall. Two types of mast cells were found: mast cells containing both tryptase and SP, and mast cells containing tryptase only. It is concluded that interactions between neuronal elements and mast cells play a significant role in the progress and maintenance of inflammatory processes in CUC.