Proteolytic activity and serum protease inhibitors in nasal secretions from adult patients with common colds.

Proteolytic activity and concentrations of serum protease inhibitors were measured in nasal secretions collected from 14 adult patients (6 males and 8 females) with common colds. Elastase concentration and fibrinolytic activity increased about three days after the onset of the colds, and there was a significant correlation between both values (p less than 0.01). Trypsin-like protease activity was very low. Of all serum protease inhibitors, inter-alpha-trypsin inhibitor could not be detected, and alpha 2-macroglobulin could be detected in only two cases. Variation of alpha 1-antitrypsin value was very similar to that of alpha 1-antichymotrypsin, and there was a significant correlation between alpha 1-antitrypsin and elastase (p less than 0.001). Phoretic patterns of crossed immuneelectrophoresis revealed the presence of alpha 1-antitrypsin-protease complex. alpha-protease inhibitors are major serum protease inhibitors in nasal secretions of persons with colds, and inhibit excess proteolytic activity of serine proteases. This protection is considered to be one of the major factors in preventing irreversible mucosal change.