E-SELECTIN LIGANDS MEDIATE TUMOR NECROSIS FACTOR-INDUCED NEUTROPHIL SEQUESTRATION AND PULMONARY-EDEMA IN GUINEA-PIG LUNGS

We have previously shown in perfused guinea pig lungs that tumor necrosis factor-alpha (TNF-alpha) pretreatment of lungs enhanced neutrophil sequestration as reflected by a 2.4-fold increase in lung myeloperoxidase (MPO) activity. Subsequent perfusion of phorbol 12-myristate 13-acetate (PMA) to activate the sequestered neutrophils produced an approximately threefold increase in the pulmonary capillary hydrostatic pressure and fulminant pulmonary edema. Using this ex vivo model of lung injury, we studied the role of three putative E-selectin ligands, sialyl-lewis X, Lewis X, and dimeric sialyl-lewis X, in mediating neutrophil sequestration and pulmonary edema. We pretreated neutrophils with monoclonal antibodies (mAbs) directed against these E-selectin ligands. Pretreatment of neutrophils with mAbs to sialyl-lewis X and Lewis X reduced the neutrophil sequestration, as evidenced by 45% and 27% reductions in MPO activity from control levels, respectively. This occurred in parallel with inhibition of neutrophil adhesion to the TNF-alpha-activated endothelial cells in vitro. The mAbs to dimeric sialyl-lewis X and an isotype-matched control mAb against lactosamines present on neutrophils had no effect on lung MPO activity and neutrophil adhesion. All mAbs to sialyl-Lewis X, Lewis X, and dimeric sialyl-lewis X reduced the increases in the pulmonary capillary hydrostatic pressure after challenge of the sequestered neutrophils with PMA and also reduced lung weight gain by 71%, 45%, and 38%, respectively. The control mAb to the lactosamines had no effect on the pulmonary capillary hydrostatic pressure and lung weight gain. These data indicate that E-selectin ligands contribute to the TNF-alpha-induced neutrophil sequestration in lungs and that adhesive interaction between E-selectin and sialyl-lewis X and its related carbohydrates is critical in the neutrophil-dependent increases in pulmonary vascular pressures and edema.