Pathology Inflammation a18eb6e3 Which one of the following is NOT true about chemical mediators: A Leukotrienes are formed by lipo-oxygenase pathway B Histamine is a preformed chemical mediator C Prostaglandin causes vasoconstriction at the site of inflammation D Thromboxane A2 is associated with platelet aggregation High-Yield Explanation Leukotrienes are formed by Lipo-oxygenase , Whereas, prostaglandins are formed by cyclo-oxygenase. PGs causes vasodilation.