Bronchial and Bronchoalveolar Inflammation in Single Early and Dual Responders after Allergen Inhalation Challenge

To characterize the cellular inflammation at the bronchial and bronchoalveolar levels, we evaluated 43 patients with asthma who were sensitized to house dust mites. On 2 consecutive days patients underwent methacholine challenge and allergen bronchial challenge. In addition, 6, 24, or 72 h after allergen challenge, fiberoptic bronchoscopy with bronchial lavage (BL) and bronchoalveolar lavage (BAL) was performed. Patients belonging to the 6-h, 24-h, or 72-h group were divided further into two subgroups: those with isolated early response to allergen (LAR⁻), and those with dual response to allergen (LAR⁺). The percentage of eosinophils and of epithelial cells in BAL fluid was significantly higher in LAR⁺ than in LAR⁻ patients in the 6-h group (p < 0.05, each comparison), but not 24 or 72 h after (p > 0.05, each comparison). Similarly, the proportion of BL eosinophils was also higher in LAR⁺ than in LAR⁻ patients, both in the 6-h and in the 24-h group (p < 0.05, each comparison). In addition, increased proportions of BL neutrophils were present in the LAR⁺ patients belonging to the 24-h group (p < 0.05). Comparing ``proximal' = BL vs ``distal' = BAL data, we found a significantly higher proportion of epithelial cells in BL compared with BAL, in both LAR⁻ and LAR⁺ subjects, either 6, or 24, or 72 h after challenge (p < 0.01, each comparison) and increased percentages of BL neutrophils and eosinophils in LAR⁺ patients (p < 0.05, each comparison), but not in LAR⁻ patients, in the 24-h group. The percentages of BL or BAL macrophages and lymphocytes did not differ significantly among the different patient groups. These data indicate that the development of LAR after allergen inhalation challenge is associated with an early recruitment of eosinophils and with epithelial desquamation in the airways. In addition, after allergen challenge epithelial desquamation is more pronounced in the proximal than in the distal airways, independently of the type of bronchial response. Accepted for publication: 7 January 1997