Effect of corticosteroids on sputum sol-phase protease inhibitors in chronic obstructive pulmonary disease.

Corticosteroids caused a reduction in the ratio of sol-phase sputum concentration to serum concentration of albumin in 12 patients with chronic obstructive bronchitis, suggesting a reduction in protein transudation. Alpha-1-antitrypsin values followed the same pattern as those of albumin in both the control and treatment periods, confirming the similar behaviour of the two proteins. The alpha 1-antichymotrypsin ratios were on average three times higher than those of albumin in the control period, confirming the presence of local mechanisms in the lung for preferentially concentrating this protein. The sputum-to-serum ratio of alpha 1-antichymotrypsin, however, rose during steroid treatment with the result that there was a selective increase in this protease inhibitor, which may be of potential benefit to such patients.