INTERACTION BETWEEN NEUTROPHILS AND ENDOTHELIUM

The endothelial permeability associated with cardiopulmonary bypass in children is due, at least in part, to an inflammatory response. Neutr ophils and their relationship with endothelium are fundamental to the production of capillary leak. This review discusses current concepts o f the mechanisms involved in adhesion between neutrophils and the endo thelium and its control. Evidence for modulation of these changes duri ng bypass in children is reviewed. We have shown that cardiopulmonary bypass in children is associated with downregulation (or shedding) of L-selectin and up-regulation of expression of CD11b/CD18. There may be a role for the cytokine interleukin-8 in the modulation of this proce ss. We have demonstrated in vitro that certain of the procedures assoc iated with bypass are associated with up-regulation of circulating neu trophil adhesion molecules and with the release of interleukin-8. Thes e factors include changes in temperature and circulation. More researc h is required to tease out the most important components of the mechan isms of adhesion, and clinical correlations must be defined.