Subtypes of bladder mast cells in interstitial cystitis

Background: Because the types of mast cells present in the bladder of patients with interstitial cystitis (IC) have not been elucidated, we have used immunohistochemical techniques to determine which of the mast cell types is present in biopsy specimens. Methods: For all patients diagnosed with IC (n = 10; female) their symptoms satisfied the criteria proposed by the National Institutes of Health criteria of IC and six patients suffering from bladder tumors were selected as control patients. Adjacent sections of paraffin-embedded tissues that had been fixed in Carnoy's solution were reacted with either antitryptase or antichymase antibodies. Results: In detrusor and in mucosa, the number of tryptase-positive and chymase-negative mast cells (MCT) was 146 +/- 25 and 81 +/- 31 cells/mm(2), respectively, and the number of tryptase-positive and chymase-positive mast cells (MCTC) was 124 +/- 50 and 54 +/- 20 cells/mm(2), respectively. These numbers were significantly greater than those of the control group. A significant negative correlation (P < 0.005; R = 0.943) was observed between the number of MCTC and the bladder capacity. The number of mast cells obtained by toluidine blue staining in detrusor and in mucosa was 95 +/- 68 and 71 +/- 39 cells/mm(2), respectively, suggesting that staining with toluidine blue underestimated the number of mast cells. Conclusions: Mast cells were significantly increased in number in both the mucosa and detrusor of bladder specimens from IC patients compared with those from control. The MCTC may be the type of mast cell dominantly present in the bladder of IC patients. The MCTC in detrusor increased with the progression of contracted bladder.