Modulation by lipid mediators of immune complex-induced lung inflammation in mice

The present study characterized a murine model of immune complex-induced pneumonitis and investigated the role of platelet-activating factor (PAF) and eicosanoids as mediators of lung neutrophil infiltration and hemorrhagic lesions. Rabbit antibodies to bovine serum albumin were injected into the airways and bovine serum albumin was injected intravenously into C3H/HePas and BALB/c mice. After 24 h, a significant increase in neutrophil infiltration and hemoglobin concentration in the bronchoalveolar lavage fluid and lung parenchyma was observed in both strains despite the C3H/HePas strain being 10 times more sensitive to PAF. Neutrophil influx and vascular lesions were not affected by pre-treatment of the mice with the PAF receptor antagonist, WEB 2170 (5-(2-chlorphenyl)carbonyl)3,4-dihydro-10-methyl-3-((4-morpholinyl)-2H,7H-cyclopenta(4,5)thieno(3,2-f)(1,2,4)-triazolo0(4,3-a)(1,4)-diazepine). In contrast, neutrophil influx and vascular lesions were increased by the cyclo-oxygenase inhibitor, indomethacin, and reduced by the inhibitor of leukotriene synthesis, MK 886 (3-[1-(4-chlorobenzyl-3-t-butyl-thio-t-isopropyl-indol-2y-1]-2-2-dimethylpropanoic acid) and by the leukotriene B-4 receptor antagonist, RO 0254094 (2-[(5-carboxypentyl)-6-[6-[3,4-dihidro-4-oxo-8-propyl-2H-1-benzopyran-7-yl)hexyl] benzenepropanoic acid). Increased levels of leukotriene B-4, leukotriene C-4/D-4, thromboxane B-2 were found in bronchoalveolar lavage fluid 4 h after induction of the reaction. There is also a tendency to increased prostaglandins E-2 levels. Neutrophil infiltration and vascular lesions in immune complex-induced pneumonitis in mice are mediated by leukotriene B-4. (C) 1998 Elsevier Science B.V. All rights reserved.