Mast cell involvement in interstitial cystitis: A review of human and experimental evidence

Interstitial cystitis (IC) is a heterogeneous syndrome of unknown etiology. Altered bladder glycosaminoglycans lining and bladder mastocytosis have be en documented in IC, The objective of this article is to critically examine the published data on bladder mastocytosis in clinical, experimental, and animal studies, with particular emphasis on morphologic evidence of mast ce ll increase and activation. The literature on bladder mastocytosis and mast cell activation in IC is critically reviewed with particular reference to staining methodology, tryptase immunoreactivity, and electron microscopy. D ata from humans and animal models of IC are included. Mastocytosis in IC is best documented by tryptase immunocytochemical staining. Standard surgical stains such as Giemsa and toluidine blue routinely underestimate the degre e of mastocytosis. Mast cells are 6- to 8-fold higher in the detrusor compa red with controls in "classic IC," and 2- to 3-fold higher in "nonulcerativ e" IC. Detrusor mastocytosis occurs in both classic and nonulcer IC, Mucosa l mast cell increase is present in nonulcerative IC. Mast cell activation w ithout typical exocytosis occurs in the mucosa and submucosa. Activation of mast cells, irrespective of bladder location or degree of mastocytosis, is significant. Mast cell-derived vasoactive and proinflammatory molecules ma y contribute to the pathogenesis of (C) 2001, Elsevier Science Inc.