Protease inhibitors in middle ear effusions.

As the presence of granulocytes in middle ear fluid in serous otitis media implicates a potential risk of extracellular release of granulocyte proteases, the main protease inhibitors in serum, alpha 1-antitrypsin, alpha 1-antichymotrypsin and alpha 2-macroglobulin, were immunochemically quantitated in such effusions. The mean concentration of alpha 1-antitrypsin was found to be higher in middle ear effusion and the mean concentration of alpha 1-antichymotrypsin slightly lower than in plasma. On comparison with albumin, however, lower values than expected were found in the middle ear fluid for the two inhibitors. The high molecular weight alpha 2-macroglobulin was significantly lower than in plasma. Furthermore a low molecular weight protease inhibitor, which is thought to be locally produced in the respiratory epithelium, was demonstrated in the effusion.