The formation of thromboxane B2, leukotriene B4 and 12-hydroxyeicosatetraenoic acid by alveolar macrophages after activation during tumor growth in the rat.

Pieces of tumor tissue were implanted subcutaneously in the right flank of BN female rats. After 3, 7, 10, 12, 14 and 17 days the lungs were lavaged and the alveolar macrophages collected. The cells were activated with the calcium ionophore A23187 and the formation of thromboxane B2 (TxB2), leukotriene B4 (LTB4) and 12-hydroxyeicosatetraenoic acid (12-HETE) determined. The formation of TxB2 decreased considerably until day 7. Thereafter, no changes occurred. The formation of LTB4 increased after the tumor implantation until day 10 and remained stable for the rest of the period, 12-HETE formation was approximately similar, with a decrease at day 12 but continued to increase after day 14. These results suggest that during tumor growth an inhibition of the cyclo-oxygenase or thromboxane synthase occurs and an activation of the C5- and C12-lipoxygenases of the alveolar macrophages.