High mannose type N-linked oligosaccharides on endothelial cells may influence β2 integrin mediated neutrophil adherence in vitro

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Abstract
We report herein on the role of N‐linked oligosaccharide processing of endothelial cell surface proteins on the adhesion of neutrophils. Monolayers of human umbilical vein endothelial cells were treated for 24 h with deoxymannojirimycin (DMJ), an inhibitor of golgi mannosidase I, which results in changes in glycoprotein processing, and then incubated with neutrophils to examine their ability to adhere to the treated endothelial cells. Treatment with DMJ, which leads to accumulation of high mannose type oligosaccharides, resulted in a twofold increase in adherence of phorbol ester (PMA) activated neutrophils compared to attachment to untreated endothelial cells. This adherence was likely mediated by the β2 integrin, Mac‐1, and could be specifically inhibited with monoclonal antibodies to ICAM‐1 and to the integrin β2 subunit. Similarly, IL‐1 treatment resulted in a β2 integrin mediated increase in neutrophil adherence to the DMJ treated endothelial cells in a dose dependent manner. However, the IL‐1 induced adherence was not significantly inhibited by the anti‐ICAM‐1 antibody, thus, suggesting the presence of other inducible components on the endothelial cell surface. Our results demonstrate that alterations in glycosylation of N‐linked oligosaccharides, resulting in the synthesis of high mannose type sugars on molecules that may interact with the β2 integrins, leads to an increased adherence of PMA activated neutrophils to endothelial cells.