Exogenous arachidonic acid metabolism in platelets from psoriatic patients

Several reports have been published on platelet hyperaggregation in psoriatic patients, which might be related to alterations in arachidonic acid (AA) metabolism by platelets. We have studied the AA metabolism pattern, total eicosanoid formation and biosynthesis rate in platelet from psoriatic patients and from normal subjects after incubation with exogenous AA. We have found no difference in the metabolic pattern of platelets. Total formation of 12-HETE was higher in the control group (p less than 0.01). The rate of synthesis of cyclooxygenase products was higher in the psoriatic group, but only that of thromboxane B2 was statistically significant (p less than 0.02). There was a close correlation between thromboxane B2 formation rate and the lag time of platelet aggregation in response to 1 mM AA (p less than 0.01). The percentage of aggregation of platelets from psoriatics was significantly higher than that from normal subjects (p less than 0.05) and the lag time was lower in psoriatic group, but the difference was not statistically significant.