Isolation and characterization of trypsin-like and chymotrypsin-like proteinases from human cholesteatoma.

The mast-cell-specific proteolytic enzymes tryptase and chymase were identified in and isolated from cholesteatoma in a ratio similar to that found in human skin. We assume that this ratio reflects a similar distribution of tryptase-containing and tryptase/chymase-containing mast cells in both these tissues. It seems conceivable that mechanisms able to trigger excessive and/or continuous mast cell degranulation in the middle ear might be causative for the formation of cholesteatoma either directly or via primed chronic inflammatory reactions. By their ability to amplify degranulation of mast cells, mast cell proteinases, in particular chymase, may contribute to the chain of events leading to the formation of cholesteatoma.