Scheme for the formation of 5-oxo-12S-HETE and 8-trans-5-oxo-12(RS)-HETE by mixtures of platelets and neutrophils. Arachidonic acid (AA) is converted to 12-HETE by 12-LO and to 5-HETE and LTA₄ by 5-LO. 12-HETE and 5-HETE can be converted to 5S,12S-diHETE by neutrophil 5-LO or platelet 12-LO, respectively, whereas 5-HETE can also be converted to 5-oxo-ETE by 5-hydroxyeicosanoid dehydrogenase (5h-dh) in neutrophils or platelets. 5-oxo-12S-HETE can be formed either by the action of 5h-dh on 5S,12S-diHETE or the actions of 12-LO on 5-oxo-ETE. The 8-trans isomers of 5-oxo-12-HETE can be formed by the actions of 5h-dh on 6-trans-LTB₄, which is converted to 8-trans-5-oxo-12R-HETE, and 12-epi-6-trans-LTB₄, which is converted to 8-trans-5-oxo-12R-HETE.