L-selectin expression on polymorphonuclear leukocytes and monocytes in premature infants: reduced expression after dexamethasone treatment for bronchopulmonary dysplasia.

We examined the effect of dexamethasone on the expression of the adhesion molecule L-selectin on circulating polymorphonuclear leukocytes (PMLs) and monocytes from premature infants with bronchopulmonary dysplasia (BPD). Nineteen infants who received dexamethasone (Dex group) and 28 who did not receive dexamethasone (no Dex group) were studied. L-selectin expression, measured as mean fluorescence intensity, was lower on circulating PMLs (5.7 +/- 0.6 vs 10.6 +/- 0.7, p < 0.001) and monocytes (7.9 +/- 0.9 vs 12.5 +/- 0.9, p < 0.02) isolated from those who had received dexamethasone. Because L-selectin is important for the recruitment of PMLs to inflammatory foci in the lungs, we speculate that one of the mechanisms by which dexamethasone reduces inflammation in BPD is by impairing the ability of leukocytes to migrate into the BPD lesions.