Early dexamethasone decreases expression of activation markers on neutrophils and monocytes in preterm infants

To investigate the effects of early dexamethasone administration on activation of circulating neutrophils and monocytes in preterm infants with respiratory distress syndrome requiring treatment with surfactant.

Neonates (n = 30) with respiratory distress were randomized to receive dexamethasone (DEX group, 29.1 +/- 1.2 wk, 1223 +/- 156 g, n = 15) from the first postnatal day, or to serve as controls (control group, 29.2 +/- 1.4 wk, 1250 +/- 148 g, n = 15). Dexamethasone was given as a 4 d course (0.5 mg kg(-1) on postnatal days 1 and 2, and 0.25 mg kg(-1) on days 3 and 4). Polymorphonuclear leucocyte (PMN) and monocyte surface expression of CD11b, L-selectin and CD14 was quantified with flow cytometry, and plasma macrophage-inflammatory protein-1alpha (MIP-1alpha) with an enzyme-linked immunosorbent assay. Blood samples were collected on days 1, 2-3 and 5-7.

In the DEX group 1/15, and in the control group 7/15 developed bronchopulmonary dysplasia (p < 0.04). PMN CD11b (median 100, range 70-190 vs 154, 96-213, p=0.01), monocyte CD14 (235, 102-433 vs 355, 219-533, p=0.01) and plasma MIP-1alpha (20 ng l(-1), 20-32 vs 37 ng l(-1), 20-70, p = 0.005) were lower in the DEX group at days 2-3. All adhesion molecule expression and plasma MIP-1alpha levels were comparable at days 5-7, with the exception of monocyte L-selectin expression levels, which remained lower in the DEX group.

In preterm infants with respiratory distress syndrome, early dexamethasone causes downregulation of PMN and monocyte activation. This may attenuate pulmonary inflammation and improve pulmonary outcome.