Differential release and effects of LTB4 in guinea-pig lung "in vitro"

LTB4 is a potent chemotactic and chemokinetic eicosanoid released by leukocytes during inflammatory reaction; in addition to this it possesses a bronchopulmonary activity in different animal species. Since cysteinyl containing leukotrienes and other eicosanoids have been shown to induce hyperreactivity of pulmonary smooth muscles, we investigated the release of LTB4 from different anatomical structures of guinea-pig lung in vitro and the possible interaction with histamine in these tissues. In fact, hyperreactivity is evidentiated by a synergism between different mediators. The ovalbumin sensitized guinea-pig lung has been brushed in order to separate lung parenchyma from bronchi and vessels which were divided into large and small preparations. The antigen challenge resulted in a statistically significant increase in LTB4 production in large bronchi and vessels, whereas in the other preparations considered the basal levels of the eicosanoid were not modified during the anaphylactic reaction. In parallel with the differential site of LTB4 release, a positive interaction between LTB4 and histamine was only observed in the pulmonary artery. These data suggest that the possible role of LTB4 in different pulmonary diseases is not confined to the airway smooth muscle but it might be related to its capacity to induce vascular hyperreactivity.