Leukotrienes B4 and C4 have distinct microcirculatory actions in vivo

Leukotriene C4 and its immediate metabolites leukotriene D4 and E4 are potent inducers of macromolecular leakage from postcapillary venules by a direct, immediate type of action. Leukotriene B4 specifically promotes leukocyte adhesion to the vascular endothelium, with subsequent diapedesis and further migration in the extravascular space. In addition, leukotriene B4 elicits a delayed type of plasma exudation that apparently is secondary to recruitment of polymorphonuclear leukocytes from the circulation. Considered together, the microvascular effects of the leukotrienes documented here strongly support the possibility that these substances are significant mediators of tissue edema and granulocyte accumulation, characteristics of the acute inflammatory reaction.