Increased expression of intercellular adhesion molecule 1 in relation to mast cells in the bladder of interstitial cystitis patients

Interstitial cystitis (IC) is a sterile, painful bladder disorder, often associated with inflammation. A defective urothelium and activated mast cells have been implicated in the pathophysiology of IC. Mast cells have been reported to induce the expression of intercellular adhesion molecules (ICAM) that are considered a necessary first step for the initiation of inflammation. We investigated the presence of ICAM-1 and its association with bladder mast cells in IC patients and controls in order to further understand their role in the pathophysiology of IC. Bladder tissue was fresh frozen and 7 m section were cut using a cryostat. Immunocytochemical detection was carried out with monoclonal antibodies directed against anti-ICAM-1 and tryptase. Twenty-one biopsies from women with IC and two from normal tissue from radical cystectomies (control) were analyzed. All IC samples were strongly positive for ICAM-1, exclusively in capillaries. Control samples were only faintly positive in fewer capillaries. Numerous mast cells were identified in the positive regions with toluidine blue or tryptase immunocytochemistry. This work may help explain why many IC patients develop sterile inflammation. It may also provide evidence further explaining the role of bladder mast cells in the pathophysiology of IC.