Cathepsin B-like thiol proteases and collagenolytic proteases in middle ear effusion from acute and chronic otitis media with effusion.

Hydrolytic activity of cathepsin B-like thiol proteases and collagenolytic proteases was measured in middle ear effusions (MEE) from pediatric patients with acute and chronic otitis media with effusion (OME). Both activities were significantly higher in MEEs from acute OME than those from chronic OME (p less than 0.01). The ratio of hydrolytic activity in the extracellular portion to the total activity in MEEs from chronic OME was also analysed in both proteases. The ratio ranged from 20 to 100% in individual cases, indicating that the degree of the release of lysosomal thiol proteases including collagenolytic proteases from leukocytes is variable in MEEs with chronic OME. The kinetics of lysosomal thiol proteases including collagenolytic proteases in acute OME seems to be much more active than that in chronic OME, and the presence of these thiol proteases appears to be an important factor leading to chronic OME.