Synthesis of eicosanoids by isolated guinea pig tracheocytes

Epithelial cells from the guinea pig trachea (tracheocytes) have been separated from the lamina propria by incubation with EDTA. Contaminating eosinophils were removed by plating on guinea pig immunoglobulin G (IgG)-coated plates. Purity of the cell suspension was assessed by electron microscopy. Enzyme immunoassay analyses of supernatants of guinea pig tracheocytes incubated with 10 microns arachidonic acid (AA) in the presence or absence of 2 microns ionophore A23187 showed that the cells released up to eight times more thromboxane, prostaglandin E2, and 6-ketoprostaglandin F1 alpha than control cells. Ionophore A23187 by itself stimulated to a smaller extent the release of these eicosanoids and did not potentiate the effect of AA. The release of cyclooxygenase products by these cells was highly modified by cell densities in the incubation media. The release of leukotrienes (LT) by stimulated epithelial cells was also investigated using reverse-phase high-performance liquid chromatography. Our results showed that the cells could not release LT on incubation with ionophore A23187 and/or AA. However, the cells released LTB4 in the medium on incubation with 2 microns LTA4. Peptido-leukotrienes were not detected. These results indicated that guinea pig tracheocytes have the cyclooxygenase and the LTA4 hydrolase but not the 5-lipoxygenase. It is postulated that tracheocytes may participate in transcellular metabolism of LTA4 generated by other cell types.