Lipocortin-1 distribution in bronchoalveolar lavage from healthy human lung: effect of prednisolone.

Lipocortin-1 (LC-1; annexin-1) may mediate some anti-inflammatory actions of the glucocorticoids, probably after binding to specific cell surface binding sites. We have quantified LC-1 levels in bronchoalveolar lavage (BAL) fluid and cells collected from seven healthy volunteers before and after 7 days of treatment with an oral glucocorticoid, prednisolone (30 mg/day). Extracellular BAL LC-1 was higher and cellular LC-1 was lower after prednisolone than before [extracellular: before, median 98 ng/mg albumin (range 48-350 ng/mg albumin); after, 236 ng/mg albumin (19-414 ng/mg albumin); P < 0.05. Cellular: before, 23.3 ng/10(6) cells (14.6-26.9 ng/10(6) cells); after, 18.0 ng/10(6) cells (122-268 ng/10(6) cells); P < 0.05]. The distribution of LC-1 within BAL cells ex vivo (cell surface = 25%, cytosol = 50%, membrane = 25%) was unaffected by prednisolone treatment. However, in adherent cells that had been cultured for 4 h, 70-80% of the LC-1 was on the cell surface. In summary, prednisolone appears to promote cellular release of LC-1. The difference in distribution of cellular LC-1 in BAL cells ex vivo and in vitro may reflect adherence and/or activation.