IgE-mediated 15-hydroxyeicosatetraenoic acid (15-HETE) generation by peripheral blood leukocytes: its association with basophil activation

INTRODUCTION Allergen-induced basophil activation has been associated with the release of several mediators and with an increased expression of CD203c molecules on basophils. AIM To assess the influence of specific allergens on the generation of 15-hydroxyeicosatetraenoic (15-HETE) from peripheral blood leukocytes in relation to basophil activation, on the basis of CD203c molecule expression and histamine release. MATERIAL AND METHODS The study included 15 patients with clinical symptoms of birch pollen allergy confirmed by a positive skin prick test with the birch allergen, and 6 healthy controls. Leukocytes isolated from peripheral blood were incubated with 3 concentrations of the birch pollen allergen (Bet v 1), anti-IgE or with ionophore A23187. RESULTS In vitro challenge of leukocytes from allergic patients with 1 ng/ml of allergen induced a significant increase in 15-HETE generation. An increase above 30% was observed in almost half the allergic patients, with mean values ranging from 40% to 46%, but not in healthy controls. Anti-IgE antibodies increased 15-HETE generation in 5 patients (termed IgE+), and the allergen induced a significant increase in 15-HETE in all patients who reacted to anti-IgE. The mean CD203c expression on basophils of the allergic patients increased after allergen challenge, but a significant increase (> 30%) was observed only in patients who demonstrated an increased expression after anti-IgE exposure. A significant correlation was seen between 15-HETE generation and histamine release induced by the highest concentration of the allergen (r = 0.95; p < 0.01). CONCLUSIONS Allergen-induced, IgE-mediated activation of basophils is associated with a significant increase in 15-HETE generation.