Soluble selectins and ICAM-1 modulate neutrophil-endothelial adhesion and diapedesis in vitro

We observed that normal plasma dramatically reduces neutrophil-endothelial adhesion. Therefore, we identified factors in plasma which might limit PMN adhesion in vitro. We found that the anti-adhesive effect was not mediated by vasoactive lipids present in plasma. Immunoprecipitation of soluble adhesion molecules, P and E-selectins and ICAM-1 restored PMN adhesion to control values. We further examined whether soluble adhesion molecules in plasma might also regulate PMN endothelial migration in response to fMLP (10(-6) M). Plasma significantly reduced PMN migration, and this effect was prevented only by the simultaneous removal of soluble P and E selectins and ICAM-1 together, but not individually. These data show that soluble selectins and ICAM-1 may regulate PMN adhesion and diapedesis, and that alterations in the levels of these molecules may regulate PMN-endothelial interactions in vivo.