Alpha 1-antichymotrypsin in infected and noninfected sputum.

alpha 1-Antichymotrypsin is a proteolytic enzyme inhibitor believed to be important for protecting tissues from proteolytic damage. Concentrations in the bronchial secretions might therefore be important in relation to the infective process. We studied the protein quantitatively and qualitatively in sputum from patients with bronchitis. In noninfected sputum the concentration of alpha 1-antichymotrypsin relative to protein albumin was 6.48 times higher than that in the serum, suggesting that local mechanisms exist to concentrate or produce this protein. In the presence of acute infections, increased protein transudation from the serum occurred. Although the absolute concentration of alpha 1-antichymotrypsin increased in the sputum, its concentration relative to albumin decreased to 2.09 times that in the serum. Two-dimensional electrophoretic studies of sputum alpha 1-antichymotrypsin showed varying proportions present as "complex," even in the noninfected samples. The electrophoretic mobility of the uncomplexed alpha 1-antichymotrypsin was generally the same as that of serum alpha 1-antichymotrypsin.