Biochemical and cellular actions of membrane lipids.

A network of intercellular signals is modulated by eicosanoids derived from arachidonate that can be supplied from either the diet or the membrane lipids. Fatty acid oxygenases controlling the first committed step in the biosynthesis of prostaglandins and leukotrienes are suppressed in normal tissues but are activated by lipid hydroperoxides. Because hydroperoxides are also produced by the action of the oxygenases, they provide positive feedback amplification during eicosanoid biosynthesis. This relationship among membrane lipids, lipid peroxides, and eicosanoids can lead to amplification of the intercellular signals mediated by cytokines and immune globulins in ways that create hyperresponsive states and lead to pathophysiology.