Cysteine proteinases in bronchoalveolar epithelial cells and lavage fluid of rat lung

Y. Ishii, Y. Hashizume, T. Watanabe, S. Waguri, N. Sato, M. Yamamoto, S. Hasegawa, E. Kominami, Y. Uchiyama

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33 Citations (Scopus)


We examined the presence of cathepsins B, H, and L in bronchoalveolar epithelial cells, including alveolar macrophages, and in bronchoalveolar lavage fluid (BALF), using immunocytochemistry and immunoblotting. By light and electron microscopy, immunoreactivity for cathepsins B, H, and L was detected in lysosomes of ciliated and non-ciliated epithelial cells of bronchi and bronchioles, and in macrophages. Immunodeposits for cathepsin H only were demonstrated in lamellar bodies of Type II alveolar epithelial cells, suggesting the cosecretion of surfactants and cathepsin H from the cells into the alveolar space. By immunoblotting, cathepsin B and H were found to be present in BALF. To further investigate the origin of these enzymes in BALF, alveolar macrophages obtained from BALF were cultured for 6 hr in a serum-free medium. Immunoblotting revealed that protein bands corresponding to the pro-form and mature form of cathepsin B and the mature form of cathepsin H were present in the culture medium. From these results, the presence of cathepsins B and H in BALF can be explained by the fact that cathepsin B is secreted from alveolar macrophages and cathepsin H is secreted mainly with surfactants from Type II cells and also from macrophages.

Original languageEnglish
Pages (from-to)461-468
Number of pages8
JournalJournal of Histochemistry and Cytochemistry
Issue number4
Publication statusPublished - 1991


  • BALF
  • Cysteine proteinases
  • Lamellar bodies
  • Lysosomes
  • Rat lung


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