PLASMA FACTORS AUGMENT NEUTROPHIL AND ENDOTHELIAL-CELL ACTIVATION DURING AORTIC-SURGERY

Lung injury following reperfusion results from endothelial damage caus ed by release of cytotoxic products by activated neutrophils (PMN) in the pulmonary microvasculature. This process is facilitated by the rel ease of pro-inflammatory cytokines and arachidonic metabolites followi ng the onset of reperfusion. This study aimed to evaluate the effect o f plasma obtained before and after revascularisation on neutrophil and endothelial cell activation. Plasma (IR plasma) was obtained from ven ous blood samples taken before and during aortic cross-clamping, and 5 , 40 and 60 min following clamp removal in seven patients undergoing e lective infrarenal aortic aneurysm resection. PMN from healthy volunte ers (n=5) were incubated with these plasma samples or with fMLP (N-for mylmethionyl-leucyl-phenylalanine) as positive control for 30 min and assessed flow-cytometrically for CD11b expression. Human endothelial c ells (ECV-304) were incubated with IR plasma for 2, 4, and 6 h or with tumour necrosis factor (TNF) (20 ng/ml) as positive control and asses sed for ICAM-1 expression. Incubation with IR plasma resulted in a sig nificant increase for pre-clamp in PMN CD11b expression. A similar tre nd was seen in endothelial cell ICAM-1 expression following 2 h incuba tion. These results indicate that reperfusion-induced endothelial dysf unction may be mediated by plasma factors released upon revascularisat ion which facilitate neutrophil-endothelial interaction through up-reg ulation of adhesion receptor expression.