Eosinophils and neutrophils modify arachidonic acid-induced relaxation of guinea-pig trachea

The influence of inflammatory cells on airway reactivity was investigated on arachidonic acid-induced relaxations of guinea-pig trachea and on arachidonic acid metabolism in guinea-pig tracheal epithelial cells. The presence of either eosinophils or neutrophils (1.0 x 10(7) cells/ml), from bronchoalveolar lavage, decreased the tracheal relaxations induced by arachidonic acid (1.0-30 mu M). The basal synthesis of prostaglandin E(2) was increased in epithelial cells (from 176 +/- 36 to 7920 +/- 898 pg/ml), eosinophils (from 360 +/- 56 to 2693 +/- 686 pg/ml) and neutrophils (from 352 +/- 81 to 4400 +/- 272 pg/ml) following incubation with arachidonic acid (10 mu M) The co-incubation of either eosinophils or neutrophils with epithelial cells, in the presence of arachidonic acid, decreased the synthesis of prostaglandin E(3) (2600 +/- 686 and 4400 +/- 272 pg/ml respectively) but increased the synthesis of thromboxane B-2 (from 60 +/- 6 to 11634 +/- 840 and 9282 +/- 485 pg/ml respectively). Similarly, when major basic protein-treated (100 mu g/ml) epithelial cells were incubated with arachidonic acid, the prostaglandin E(2) synthesis decreased (75%) but thromboxane B-2 synthesis was unaffected. The results suggest that eosinophils and neutrophils may impair arachidonic acid metabolism in guinea-pig epithelium in favor of production of bronchoconstrictor prostanoids.