Late-phase asthmatic reaction to inhaled allergen is associated with early recruitment of eosinophils in the airways

To determine whether a link exists between the recruitment of inflammatory cells in the airways and the development of the late-phase asthmatic reaction, we studied with bronchoalveolar lavage 54 asthmatic patients either at baseline (10 patients) or 4 h (11 patients), 24 h (13 patients), and 72 h (20 patients) after allergen inhalation challenge. Among the patients studied 4 h after allergen challenge, five were known to have a late-phase asthmatic response and showed a significant increase in the number and percentage of eosinophils in bronchoalveolar lavage compared with either patients without late-phase response (p <0.05) or unchallenged patients (p <0.01). Both the number and the percentage of eosinophils in bronchoalveolar lavage were also increased (p <0.05) in patients without a late-phase asthmatic reaction studied 24 h but not in those studied 4 h after allergen challenge. The numbers and the percentages of macrophages, neutrophils, or lymphocytes did not differ significantly among the different groups of patients. Of the patients studied 4 and 24 h after allergen challenge, only those with a late-phase asthmatic response showed an increased airway responsiveness to methacholine 1 h before bronchoalveolar lavage. We conclude that the development of the late-phase asthmatic response to allergen inhalation challenge and the allergen-induced increase in airway responsiveness are associated with an early recruitment of eosinophils in the airways.