Increased levels of oxidized methionine residues in bronchoalveolar lavage fluid proteins from patients with idiopathic pulmonary fibrosis

Am Rev Respir Dis. 1991 Feb;143(2):271-4. doi: 10.1164/ajrccm/143.2.271.


Phagocytic cells are believed to play a crucial role in the development of inflammatory lung diseases. We assumed that the oxidation of methionine (met) to methionine sulfoxide [met(O)] by oxygen-derived free radicals released from phagocytes is one parameter to identify the oxidative mechanisms of lung injury. To test this hypothesis we determined the molar ratio of met(O)/met in the soluble protein fraction of bronchoalveolar lavage (BAL) fluids from healthy nonsmokers and from nonsmoking patients with idiopathic pulmonary fibrosis (IPF) or sarcoidosis. The met(O)/met ratio of the healthy nonsmoker group (n = 11) was 0.046 +/- 0.008 (mean +/- SEM). In contrast, the met(O)/met ratio of the nonsmoking IPF group (n = 11) was significantly increased to 0.223 +/- 0.053 (p less than 0.0002). The BAL fluids of this group showed strongly increased numbers of neutrophils but normal numbers of alveolar macrophages (AM). In the sarcoidosis group (n = 10) the met(O)/met ratio (0.048 +/- 0.010) was not significantly different from control values. A close relationship was found between the met(O)/met ratios and the relative as well as the absolute neutrophil counts (r = 0.86; p less than 0.0002; n = 22). In contrast, no significant correlation was found between the met(O)/met ratios and the absolute AM counts (r = 0.22; p = 0.32; n = 22). We conclude that mechanisms of oxidative lung injury in IPF can be characterized by oxidation of met and that this oxidation may be mediated by neutrophils.

MeSH terms

  • Adult
  • Aged
  • Aging / physiology
  • Bronchoalveolar Lavage Fluid / cytology
  • Bronchoalveolar Lavage Fluid / metabolism*
  • Drug Residues
  • Female
  • Humans
  • Leukocyte Count
  • Lymphocytes / pathology
  • Male
  • Methionine / analogs & derivatives
  • Methionine / metabolism*
  • Middle Aged
  • Neutrophils / pathology
  • Oxidation-Reduction
  • Proteins / metabolism*
  • Pulmonary Fibrosis / metabolism*
  • Pulmonary Fibrosis / pathology
  • Reference Values
  • Sarcoidosis / metabolism
  • Sarcoidosis / pathology


  • Proteins
  • Methionine
  • methionine sulfoxide