Detachment of endothelial cells by polymorphonuclear leukocytes in vitro: potentiation by antibody coating and prevention by inflammatory exudate.

A widely advocated hypothesis suggests that polymorphonuclear leukocytes release enzymes at sites of inflammation which in turn cause tissue damage, especially vasculitis. To test this we isolated and grew human endothelial cells and labelled them with chromium-51. Polymorphonuclear leukocytes were separated from whole blood and added to the labelled endothelial cells. Upon incubation with the polymorphonuclear leukocytes the endothelial cells rapidly detached but were not lysed. Detachment was prevented by the addition of small amounts of inflammatory exudate. Prior coating of endothelial cells with a specific antibody accelerated detachment of the cells by polymorphonuclear leukocytes but this was still prevented by addition of inflammatory exudate in low concentration. In a separate experiment extracellular basement membrane synthesized in vitro by endothelial cells was labelled by incubating the cells with 14C-proline. Polymorphonuclear leukocytes caused release of 14C but this was again prevented by addition of either inflammatory exudate or serum. We conclude that polymorphonuclear leukocytes alone could cause vascular intimal damage in vivo if inhibitors, which are present in serum and inflammatory exudate, are excluded or overwhelmed.