Contribution of secretory leukocyte proteinase inhibitor to the antiprotease defense system of the peripheral lung: effect of ozone-induced acute inflammation

Am J Respir Crit Care Med. 1995 Nov;152(5 Pt 1):1592-8. doi: 10.1164/ajrccm.152.5.7582300.


Secretory leukocyte protease inhibitor (SLPI) and elafin are structurally similar, low-molecular-weight antiproteases produced in the lung. We have developed a simple method for distinguishing the antiprotease activities of SLPI and elafin in lung lavage fluid from those of alpha 1-antitrypsin (alpha 1-AT) that is based on the resistance of the low-molecular-weight antiproteases to inactivation by cetyltrimethylammonium bromide. In a study of 23 healthy, nonsmoking volunteers, we found that the low-molecular-weight antiproteases accounted for 22 +/- 2% (mean +/- SEM, n = 23) of the total neutrophil elastase-inhibitory capacity of human bronchoalveolar lavage fluid (BALF). Elafin activity was below the limit of detection. SLPI activity (as measured by inhibition of alpha-chymotrypsin) accounted for 72 +/- 4% (mean +/- SEM, n = 23) of the low-molecular-weight antiprotease activity in BALF. Measurements of SLPI in the lavage fluid samples by enzyme-linked immunosorbent assay (ELISA) agreed closely with values obtained by measuring the activity of this inhibitor. The activity of the low-molecular-weight antiproteases decreased significantly (p < 0.05), from 9.0 +/- 0.8 to 7.0 +/- 0.6 pmol of neutrophil elastase inhibited per mL (mean +/- SEM, n = 23), following acute ozone exposure.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acute Disease
  • Adult
  • Bronchoalveolar Lavage Fluid / chemistry
  • Bronchoscopy
  • Cross-Over Studies
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Lung / drug effects
  • Lung / enzymology*
  • Male
  • Molecular Weight
  • Ozone / adverse effects*
  • Pneumonia / chemically induced
  • Pneumonia / enzymology*
  • Proteinase Inhibitory Proteins, Secretory
  • Proteins / analysis
  • Proteins / physiology*
  • Secretory Leukocyte Peptidase Inhibitor
  • Serine Proteinase Inhibitors / analysis
  • Serine Proteinase Inhibitors / physiology*
  • Single-Blind Method


  • Proteinase Inhibitory Proteins, Secretory
  • Proteins
  • SLPI protein, human
  • Secretory Leukocyte Peptidase Inhibitor
  • Serine Proteinase Inhibitors
  • Ozone