Abnormal interaction of alpha 1-antitrypsin and leukocyte elastolytic activity in patients with chronic obstructive pulmonary disease.

The interaction of serum alpha 1-antitrypsin with leukocyte elastolytic activity was examined in 71 patients with chronic obstructive pulmonary disease and 46 normal subjects. Residual elastolytic activity was present despite adequate amounts of alpha1-antitrypsin in 33 of the 71 patients compared to 6 of the 46 normal control subjects (P less than 0.001). This elastolytic activity was completely abolished by a specific human leukocyte elastase inhibitor. A crossover study designed to detect the source of this abnormal activity revealed that the plasma fraction containing alpha 1-antitrypsin was responsible for inadequate inhibition in 30 of the 39 cases. The residual elastolytic activity from a given patient did not correlate with the serum alpha 1-antitrypsin concentration, alpha 1-antitrypsin phenotype, or history of smoking. Our data suggest that the abnormal interaction of alhpa 1-antitrypsin with leukocyte elastolytic activity is an important additional variable in the gensis of chronic obstructive pulmonary disease.