Blood and bronchoalveolar eosinophils in allergic subjects after segmental antigen challenge: Surface phenotype, density heterogeneity, and prostanoid production

Eosinophil infiltration into the airways has been implicated in the pathophysiology of asthma. To improve our understanding of the function of eosinophils in asthma, we have compared the phenotype and function of eosinophils obtained simultaneously from blood and bronchoalveolar lavage (BAL) of allergic subjects 19 hours after segmental lung allergen challenge. Eosinophils were purified by discontinuous density gradient centrifugation, and their distribution at various layers was quantitated. Eosinophils at the 1.080 to 1.085 gm/ml interfaces from blood and BAL (purity > 70%) were analyzed by immunofluorescence and flow cytometry for several surface markers including adhesion-activation antigens. Eosinophils in BAL from antigen-challenged sites were markedly increased compared with control diluent-challenged BAL sites (0.3% ± 1% vs 28.1% ± 9.7%, n = 12, p < 0.002), and a greater percentage were hypodense (specific gravity