Neutrophil-mediated Lung Injury in Rats

Introduction Two murine monoclonal antibodies (CL-3 and CL-37, both F(ab')2) to human endothelial-leukocyte adhesion molecule-i (ELAM-1) were found to react immunohistochemically with rat pulmonary artery endothelial cells that had been pretreated with tumor necrosis factor (TNFa). CL-3, but not CL-37, blocked in vitro adherence ofneutrophils to TNFa-treated endothelial cells and the killing of TNFa-treated rat endothelial cells by phorbol ester activated neutrophils. In rats treated systemically with CL-3, there was a 70% reduction in accumulation of neutrophils in glycogen-induced peritoneal exudates. Treatment of animals with CL-37 anti-ELAM-1 did not reduce neutrophil accumulation under the same conditions. When IgG immune complex deposition was induced in dermis and in lungs of rats, treatment with CL-3 anti-ELAM-1 markedly reduced vascular injury as measured by changes in vascular permeability (leakage of 1251-albumin) and hemorrhage (extravasation of 51Cr-red blood cells). The protective effects of CL-3 antiELAM-1 were related to greatly diminished recruitment ofneutrophils (as assessed morphologically, by tissue extraction of myeloperoxidase, and by retrieval, via bronchoalveolar lavage, of neutrophils from lung). CL-37 had no protective effects in vivo after deposition ofimmune complexes in lung. Using either CL-3 or CL-37 anti-ELAM-1, immunohistochemical analysis of lungs undergoing IgG immune complex-induced injury revealed a striking upregulation of ELAM-1 in the lung vasculature (venules and interstitial capillaries), with a peak intensity developing between 3 and 4 h after deposition of immune complexes in lung. Vascular beds of spleen, liver, and kidney failed to show upregulation ofELAM-1 under these same conditions. The immunohistochemical reactivity of rat lung was abolished if the anti-ELAM-1 preparation was first absorbed with monolayers of human umbilical vein endothelial cells that had been pretreated with TNFa. Untreated human endothelial cells failed to cause loss oflung reactivity ofthe anti-ELAM-1 preparation. These data indicate that ELAM-1 is upregulated in the pulmonary vasculature of rats during deposition of immune complexes and that ELAM-1 appears to play an obligate role in the recruitment of neutrophils. (J. Clin. Invest. 1991. 88:13961406.)