Inhibitory capacity of alpha 1 antitrypsin in lung secretions: variability and the effect of drugs.

The inhibitory function of alpha 1 antitrypsin (alpha 1AT) has been studied in the lung secretions of 31 patients with chronic obstructive bronchitis. The inhibitory capacity for a single sample showed a wide range (median 0.13 micrograms porcine pancreatic elastase (PPE) inhibited per microgram alpha 1 antitrypsin; range 0-0.55 micrograms), and all but five of 86 samples studied were capable of inhibiting some porcine pancreatic elastase. No sample showed free elastase activity, however. The inhibitory capacity, studied in six patients over five consecutive days, varied daily within the same individual (coefficient of variation 9.0-108.9%). Corticosteroid treatment (40 mg prednisone daily) increased the inhibitory capacity of sputum alpha 1 antitrypsin in 10 patients (2p less than 0.05) from a median value of 0.13 micrograms PPE inhibited per microgram alpha 1AT (range 0.06-0.36) before treatment to 0.22 micrograms PPE inhibited per microgram alpha 1AT (range 0.09-0.65) after treatment. The inhibitory capacity of sputum was higher than in the corresponding bronchoalveolar lavage sample from the same patient (2p less than 0.05; n = 10). The median value for sputum was 0.22 micrograms PPE inhibited per microgram alpha 1AT (range 0-0.55) and the value for lavage fluid was 0.07 micrograms PPE inhibited per microgram alpha 1AT (range 0-0.27).