Neutrophil lysosomal elastase activity in normal subjects and in patients with chronic obstructive pulmonary disease

Neutrophil lysosomal elastase activity was measured in a group of 31 asymptomatic adults (12 men, 19 women) with Pi M phenotype and normal lung function, 9 subjects (7 men, 2 women) with normal lung function and phenotypes other than Pi M, and a group of 42 patients (25 men, 17 women) with chronic obstructive pulmonary disease, 35 of whom had Pi M phenotype and 7 phenotypes associated with alpha ₁-antitrypsin deficiency. Chronic obstructive pulmonary disease was diagnosed by history and radiologic, spirometric, and blood gas characteristics of chronic airway obstruction. Neutrophil lysosomal elastase activity was measured using oxalic-acid solubilized, ligamentum nuchae elastin substrate. The average 570 nm Δ absorbency per min μg of protein for this activity in control subjects with M phenotype was 50 ± 15.6 corresponding to 793 ± 242 microunits of pancreatic elastase per μg of lysosomal protein as compared to Δ absorbency per min of 71 ± 32.9, which corresponds to 1,125 ± 522 microunits of pancreatic elastase equivalents per μg of lysosomal protein in patients with chronic obstructive pulmonary disease (P < 0.001). If the patients with chronic obstructive pulmonary disease who have phenotype other than Pi M are excluded, the mean Δ absorbency per min of the patients with Pi M phenotype is 73.4 ± 33.7, which corresponds to a pancreatic elastase equivalent activity of 1,163 ± 534 microunits per μg of lysosomal protein. Reproducibility of neutrophil lysosomal elastase activity was determined by repeat tests in the same subjects at intervals of one to 12 months and showed a coefficent of variation of 21 percent for control subjects and 38 per cent for patients with chronic obstructive pulmonary disease. No differences between smokers and nonsmokers were demonstrable in neutrophil lysosomal elastase in either normal subjects or patients. Significantly greater degrees of neutrophil lysosomal elastase activity in patients with Pi M phenotype and chronic obstructive pulmonary disease suggest a possible role for circulating elastase activity as a mechanism for damage to lung elastin in the pathogenesis of pulmonary emphysema.