Differences in elastase-binding activity of alpha 1-protease inhibitor and alpha 2-macroglobulin for asthma patients and control subjects with various alpha 1-protease inhibitor phenotypes.

Forty-two adult patients with asthma and 30 control subjects were investigated for elastase-binding capacities of alpha 1-protease inhibitor and alpha 2-macroglobulin in plasma. The binding activities of alpha 1-protease inhibitor and alpha 2-macroglobulin in asthmatic patients with the M phenotype for the alpha 1-protease inhibitor differed in their relationship to the values in control subjects with the same phenotype [less alpha 1-protease inhibitor for asthmatics (35.1 +/- 1.8) than for controls (42.9 +/- 2.0 kU/L) (P < 0.001); more alpha 2-macroglobulin for asthmatics (6.9 +/- 0.3) than for control subjects (5.9 +/- 0.4 kU/L) (P < 0.03)]. In contrast, the patients with a deficiency allele (S, V, or Z) for alpha 1-protease inhibitor had lower activities of both alpha 1-protease inhibitor [22.1 +/- 0.1 vs 42.9 +/- 2.0 kU/L (P < 0.001)] and alpha 2-macroglobulin [4.6 +/- 0.6 vs 5.9 +/- 0.4 kU/L (P < 0.001)] than did the control subjects with the M phenotypes. The relevance of the results to the pathogenesis of asthma is discussed.