Lysosomal enzymes from polymorphonuclear leukocytes and proteinase inhibitors in patients with cystic fibrosis

Am Rev Respir Dis. 1986 Jul;134(1):49-56. doi: 10.1164/arrd.1986.134.1.49.


In serum and sputum samples from 15 patients with cystic fibrosis (CF) suffering from chronic Pseudomonas aeruginosa lung infections, concentrations and/or activities of elastase derived from polymorphonuclear leukocytes (PMN), cathepsin G, myeloperoxidase (MPO), and superoxide dismutase (SOD), as well as concentrations of the proteinase inhibitors alpha 1-proteinase inhibitor (alpha 1-PI) and alpha 2-macroglobulin (alpha 2-M), were determined. High enzyme concentrations compared with those in normal control subjects were found for PMN elastase (mean, 96.1 +/- 91.7 micrograms/ml), cathepsin G (mean, 5.9 +/- 6.0 micrograms/ml), and MPO (mean, 138.0 +/- 177 micrograms/ml) in patients' sputum samples. Superoxide dismutase was not detectable in any of the sputum specimens (below 1 ng/ml). Proteinase inhibitor concentrations were elevated in serum samples (alpha 1-PI: mean, 3,457 +/- 1,084 micrograms/ml; alpha 2-M: mean, 4,835 +/- 1,334 micrograms/ml). Means of 61 +/- 38 micrograms/ml alpha 1-PI and 29 +/- 31 micrograms/ml alpha 2-M were present in the sputum specimens. Both proteinase inhibitors were functional in the serum samples. However, sputum alpha 1-PI was proteolytically degraded, as shown by western blot technique, and was not able to bind 125I-labeled PMN elastase, as shown by autoradiography. Only 10.9 +/- 8.5% of the total alpha 1-PI in the sputum samples was complexed to PMN elastase and 3.6 +/- 3.2% to cathepsin G. On the other hand, 96.2 +/- 96.8% of the total PMN elastase and 78.0 +/- 100% of cathepsin G were unbound in the sputum samples. The study suggests that the imbalance between PMN proteinases and their inhibitors is due to inactivation of alpha 1-PI in the sputum caused by proteolytic or oxidative attack from PMN enzymes.

MeSH terms

  • Blood Proteins / metabolism
  • Cathepsin G
  • Cathepsins / metabolism
  • Cystic Fibrosis / complications
  • Cystic Fibrosis / metabolism*
  • Humans
  • Neutrophils / enzymology*
  • Pancreatic Elastase / metabolism
  • Peroxidase / metabolism
  • Protease Inhibitors / metabolism*
  • Pseudomonas Infections / complications
  • Respiratory Tract Infections / complications
  • Serine Endopeptidases
  • Sputum / analysis
  • Superoxide Dismutase / metabolism
  • alpha 1-Antitrypsin
  • alpha-Macroglobulins / metabolism


  • Blood Proteins
  • Protease Inhibitors
  • alpha 1-Antitrypsin
  • alpha-Macroglobulins
  • Peroxidase
  • Superoxide Dismutase
  • Cathepsins
  • Serine Endopeptidases
  • CTSG protein, human
  • Cathepsin G
  • Pancreatic Elastase