Defective platelet lipid peroxidation in myeloproliferative disorders: a possible defect of prostaglandin synthesis.

Platelet lipid peroxidation induced by the sulphydryl blocking reagent n-ethylmaleimide [NEM] was measured by production of malonyldialdehyde [MDA]. Lipid peroxidation was decreased in five of 10 patients with proven myeloproliferative disease. The low levels of lipid peroxidation correlated well with in vitro and in vivo tests of platelet function and the bleeding and bruising problems. The reduction in lipid peroxidation with NEM may be due to one or more of the following: [i] an aged platelet population; [ii] an abnormal cell line; [iii] a reduction of the cyclo-oxygenase enzyme activity in the platelet prostaglandin synthetic pathway; [iv] a reduction of the substrate for platelet prostaglandin synthesis, Arachidonic acid; and [v] an abnormality of phospholipase A activation.