Corticosteroids increase lipocortin I in BAL fluid from normal individuals and patients with lung disease.

Lipocortin I is a corticosteroid-inducible protein that has potent anti-inflammatory activity. To determine whether lipocortin I is present on the epithelial surface of the human lung, we used a specific polyclonal antibody by the technique of Western blotting to evaluate bronchoalveolar lavage (BAL) fluid of normal individuals and patients with idiopathic pulmonary fibrosis. Lipocortin I was a normal constituent of the epithelial surface of the normal lung and comprised 0.23 +/- 0.03% of BAL fluid proteins. Four separate immunoreactive species were detected, at 37, 36, 34, and 33 kDa, consistent with previously published results. Corticosteroids increased the amounts of lipocortin present in normal volunteers and in patients with idiopathic pulmonary fibrosis. These results demonstrate that lipocortin I is normally present in the human lung and further suggest that lipocortin I may be an important modulator of the anti-inflammatory effects of corticosteroids in the lung.