LIPOPOLYSACCHARIDE-INDUCED CD11B-MEDIATED NEUTROPHIL-ENDOTHELIAL ADHESION IS NOT REQUIRED FOR POLYMORPHONUCLEAR CELL PRIMING

Abstract

Previous work has implicated both neutrophil-endothelial cell (PMN-EC) adhesion and PMN priming (enhanced superoxide production following activation) in the development of postinjury adult respiratory distress syndrome (ARDS) and multiple organ failure (MOF). CD11B, a member of the integrin family of PMN surface receptors, has been alleged to have a prominent role in these inflammatory PMN-EC processes. The purpose of the present study was to test the hypothesis that CD11B-mediated PMN-EC adhesion is necessary for endotoxin (LPS)-induced PMN priming. Human neutrophils, isolated by Percoll gradient centrifugation, were exposed to LPS (100 ng/mL). At fixed times over 120 minutes (a) superoxide following fMLP activation (i.e., priming), (b) PMN-EC adhesion, and (c) expression of CD11B were assayed. Superoxide production was measured by cytochrome c reduction, PMN-EC adhesion with indium-labelled PMN adherence to human umbilical vein endothelial cell (HUVEC) monolayer cultures, and CD11B expression with fluorescent labelled anti-CD11B (60.1) antibodies. The PMN-EC adhesion was biphasic, with an early maximum at 15 minutes followed by a nadir at 60 minutes and secondary rise through 120 minutes of LPS exposure. CD11B expression changed dramatically in temporal association with early PMN-EC adhesion, but the secondary increase in adhesion was associated with only a mild rise in CD11B expression. PMN priming increased after a latency of 15 minutes to a maximum of 800 nmol/10(6) cells/min after 60 minutes of LPS exposure.(ABSTRACT TRUNCATED AT 250 WORDS)