1 alpha, 25-Dihydroxyvitamin D3 decreased ICAM-1 and ELAM-1 expressions on pulmonary microvascular endothelial cells and neutrophil motivation.

Preincubation of pulmonary microvascular endothelial cells (PMVECs) with platelet activating factor (PAF) for 3.5 h increased the adhesion rate of polymorphonuclear leukocytes (PMNs) to PMVECs from 57.3 to 72.8% (P < 0.01). Coincubations of 1 alpha, 25-dihydroxyvitamin D3 (VD) or MC903 (VD analog) decreased the ability of PAF to increase PMN-PMVEC adhesion rate significantly. Preincubation of PMNs with PAF also increased PMN-PMVEC adhesion rate. Coincubation of VD but not MC903 blocked PAF-induced adherence of PMNs to PMVECs. Both VD and MC903 decreased PAF-increased expression of ICAM-1 on PMVECs, PMN chemotaxis to zymosan activated serum and histamine, and PMN aggregation induced by PAF significantly. VD but not MC903 decreased the expression of ELAM-1 on PMVECs. VD and MC903 did not affect PAF-induced release of acid phosphatase from PMNs. The results suggest that VD may be a good drug to inhibit PMN motivation by acting on both ECs and PMNs.