Eicosanoid synthesis by alveolar macrophages in rats with malignant mammary tumors: differences in rats treated with...

Eicosanoid synthesis by alveolar macrophages (AM), harvested from tumor bearing animals, was measured after tumor inoculation in rats treated with or without carrageenan (carra), an immunomodulating agent. After incubation of the cells with [14]C-arachidonic acid and the Ca-ionophore A23187, samples were measured by high pressure liquid chromatography (HPLC). From the HPLC profiles the lypoxygenase products, 12-hydroxyeicosatetraenoic acid (12-HETE), 15-HETE, and leukotriene-B4 (LTB4) were determined as well as the cyclooxygenase products, prostaglandin (PG)E2, PGF2 alpha and TXB2. After tumor inoculation AM-synthesis of lipoxygenase products tended to increase to values twice those of the base line values, whereas cyclooxygenase products showed subnormal values. In the non treated animals, 10 days after tumor inoculation, statistically significant increases in 12- and 15-HETE, LTB4 and PGE2 were observed when compared with carra treated animals. Later measurements did not show these differences in AM metabolism. AM metabolism was (negatively) correlated with the number of macrophages, which was particularly evident in the correlation with 12-HETE synthesis.