Rapid immobilisation of rolling neutrophils by interleukin-8 and
platelet activating factor bound to endothelial cells.
Rainger, G. E., A. Fisher, and G. B. Nash.
Department of Physiology, The Medical School,The University of
Birmingham, Birmingham, UK; Department of Clinical Engineering, Royal
Liverpool University Hospital, Liverpool, UK
APStracts 3:0314H, 1996.
The kinetics of the response of integrins to activating signal(s) must
be rapid to ensure that rolling neutrophils are localised at sites of
inflammation. From video records we analysed the adhesion of
individual neutrophils in a flow-based in vitro model of endothelial
hypoxia and reoxygenation. There were numerous rolling interactions
between flowing neutrophils and P-selectin on human umbilical vein
endothelial cells (HUVEC) after hypoxia, but 90% lasted for less than
1 second, with approximately 30% converted to stationary attachment
via [beta]2-integrin(s). Interleukin-8 (IL-8) and platelet activating
factor (PAF) were responsible for neutrophil activation in this model
(Rainger et al, Am. J. Physiol. 1995. 38: H1398-H1406). In the
presence of a PAF-receptor antagonist, IL-8 acting alone induced
conversion of rolling to stationary adhesion in as little as 80 ms
after initial attachment of a neutrophil with a median response time
of 240 ms. In the presence of a monoclonal antibody which neutralised
IL-8 activity, PAF acting alone required a minimum duration of
rolling of 560 ms to promote stationary adhesion with a significantly
longer median duration of 720 ms. In a reconstituted model, treatment
of endothelial cells with hydrogen peroxide induced short-lived
rolling of neutrophils supported by P-selectin . Exogenously added
IL-8 and/or PAF bound to the endothelial surface and successfully
induced immobilisation of neutrophils. Rapid and distinct kinetics of
conversion to stationary adhesion were again observed for IL-8 or
PAF. Thus, although endothelial-presented signals differed in their
rate of action, neutrophils could be localised within one or two
endothelial cell diameters of their initial adhesive contact point.
Received 19 March 1996; accepted in final form 16 July 1996.
APS Manuscript Number H264-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 4 August 1996