Lipoxygenase products from polymorphonuclear leukocytes and epithelial cells of human saliva

Physiological mixtures of salivary cells from 10 volunteers were examined for lipoxygenase products of exogenous arachidonic acid, the intracellular penetrability of which was enhanced by ethanol. Leukotriene B4 and its nonenzymatically produced isomers as well as 5-, 12-, and 15-hydroxyeicosatetraenoic acids (HETE) were produced in all samples. Their identity was confirmed by retention time on reverse-phase high-performance liquid chromatography, ultraviolet spectroscopy, and in the case of 12-HETE, by gas chromatography/mass spectrometry. In order to determine the absolute stereo-chemistry of 12-HETE, its (-)-menthoxycarbonyl derivative was prepared and subjected to oxidative ozonolysis, methylation, and finally gas chromatography. The results indicate that the original configuration is 12(S)-HETE. The production of leukotriene B4 correlated directly with the age of the donor while production of 15-HETE varied inversely with age. Alternative stimulation of lipoxygenase production by ionophore A23187 also resulted in substantial amounts of leukotriene B4 but the amount of 12-HETE produced was less than 2% of the amount generated with the ethanol/arachidonic acid method. This would suggest that 12-HETE production took place predominantly in cells which were not capable of being stimulated by the ionophore. These results point to the epithelial cells, rather than platelets, as the source. The presence of epithelial cells and neutrophils in the saliva, both of which have active lipoxygenase activity, provide the potential for cell interactions of a regulatory nature.