Rapid static adhesion of human naïve neutrophil to naïve xenoendothelium under physiologic flow is independent of Galα1,3-gal structures

Abstract

Adhesion interactions under flow have long been known to depend on applied wall shear stress. We investigated the ability of human naïve neutrophils to adhere to xenogeneic endothelial cells under static and flow conditions. We demonstrate that human naïve neutrophils bind to xenogeneic endothelial cells under flow conditions. This binding is dependent on the applied stress and is independent of Galα1,3-gal structures, ICAM-1, or its counter ligands LFA-1α and Mac-1. The binding was rapid and is characterized by stationary attachment with no obvious rolling or change in morphology. This binding leads to a transient increase in intracellular-free calcium levels in xenogeneic but not allogeneic-endothelial cells with occasional oscillations that persist long after the initial contact between the two cell types. Previous activation of xenoendothelium by autologous serum or human TNF-α augments binding of human naïve neutrophils to the endothelial cells. Our data suggest novel interaction sites between the xenogeneic endothelial cells and human naïve neutrophils.