IMMUNOPHENOTYPING OF EOSINOPHILS RECOVERED FROM BLOOD AND BAL OF ALLERGIC ASTHMATICS

Studies of bronchoalveolar ravage (BAL) fluid from patients with aller gic asthma have demonstrated active migration of eosinophils into the bronchial lumen after allergen challenge. The mechanisms mediating thi s eosinophil infiltration and cell activation are largely unexplained. The expression of several cell-surface molecules was measured on eosi nophils derived from blood and BAL fluid 4 h after an allergen-induced early asthmatic reaction in order to find indications for a role of t hese molecules during extravasation to and activation in the bronchial compartment. Nine patients with allergic asthma participated in the s tudy An eosinophil-specific, high-depolarization signal enabled us to measure expression on eosinophils in a fluorescence activated cell sor ter (FACS) analysis without isolation of these cells. Eosinophils reco vered from BAL showed a different phenotype than blood eosinophils; up regulation of CR-3, p150/95, CD67, and CD63, and downregulation of L-s electin indicate that the cells are activated in terms of degranulatio n. Up-regulation of intercellular adhesion molecule-1 (ICAM-1), LFA-3, and human leukocyte antigen II (HLA-II) might enable cell-cell contac t between T-lymphocytes and eosinophils, probably leading to immunomod ulation and cell activation. The finding that eosinophils in BAL are a ctivated and can interact with T cells is further evidence for the pro inflammatory role of these cells in allergic asthma.