Effects of alpha-tocopherol on platelet membrane function in cystic fibrosis.

Patients with cystic fibrosis and their parents were reported to have abnormal platelet aggregation responses to prostaglandin E1. To determine whether this is a property of the platelets, we studied the adenosine 3':5'-cyclic monophosphate (cAMP) response of washed platelets to prostaglandin E1. The cAMP response to prostaglandin E1 was the same in platelets from obligate heterozygotes for cystic fibrosis and from those of healthy controls. Patients with cystic fibrosis who had deficient vitamin E levels (plasma alpha-tocopherol, less than 500 micrograms/dl) had significantly (p less than 0.01) reduced platelet cAMP response to prostaglandin E1 compared with patients who had sufficient vitamin E, and supplementation with water-miscible vitamin E in these patients resulted in significant increases in plasma alpha-tocopherol levels (p less than 0.01) and in cAMP response to prostaglandin E1 (p less than 0.05). Plasma alpha-tocopherol levels correlated significantly with platelet cAMP response to prostaglandin E1 in patients with cystic fibrosis (r = 0.58, p less than 0.05). However, plasma alpha-tocopherol level was unrelated to the lymphocyte and granulocyte cAMP response to prostaglandin E1 or to the platelet cAMP response to alpha 2-adrenergic stimulation. Our data suggest that patients with cystic fibrosis have no inherited defect in platelet cAMP response to prostaglandin E1. In patients who have sufficient vitamin E, cAMP responses to prostaglandin E1 are normal in all the formed elements of the blood.