Hydroxyethyl starch inhibits neutrophil adhesion and transendothelial migration

A resuscitation strategy that significantly alters the state of neutrophil (PMN) activation may impact organ function and survivability after shock. Various resuscitative fluids have been shown to elicit a severe immune activation and an upregulation of cellular injury markers, whereas other fluids have been shown to be protective. Recent studies have demonstrated that hydroxyethyl starch (HES), an artificial colloid, may exert significant anti-inflammatory effects, whereas conflicting studies with the same substance have shown an increase in PMN activation. Successful manipulation of the early immune events associated with hemorrhage and resuscitation will require a better understanding of the possible pro- or anti-inflammatory effects of resuscitation fluids. Our study investigated the effect of HES directly on PMN and cultured vascular endothelial cells in vitro. The effect of HES on PMN surface expression of CD11b and L-selectin was measured by flow cytometry. PMN activation response to HES was measured using a shape-change assay in response to formyl-methionyl-leucyl-phenylalanine (f-MLP). The effect of HES on endothelial cell surface expression of E-selectin, P-selectin, vascular cell adhesion molecule-1(VCAM-1), and intracellular adhesion molecule-1 (ICAM-1) was evaluated by enzyme-linked immunoabsorbant assay. PMN rolling, adhesion, and migration events were measured using direct microscopy under conditions simulating microvascular flow. PMN surface expression of CD11b and L-selectin in whole blood samples and isolated PMNs were unaffected by exposure to HES. HES had no effect on the normal f-MLP dose-dependent increase in PMN activation. In the absence of IL-1 stimulation, there was a small but statistically significant (P < 0.05) increase in ICAM-1 after exposure to HES. After stimulation with IL-1 (10 U/mL), HES had no effect on the expression of P-selectin, E-selectin, ICAM-1, or VCAM-1. Under simulated microvascular flow conditions in vitro, HES significantly diminished the PMN tethering rate (P < 0.05) and the transendothelial migration rate (P < 0.05) in a dose-dependent manner. HES significantly alters the function of the PMN at the interface of the PMN responding to activated endothelium. The effect occurs, surprisingly, without a coincident effect on the state of PMN activation or a significant change in the surface expression of the adhesion molecules responsible for PMN-endothelial interaction.