Early Changes in T Lymphocytes Recovered by Bronchoalveolar Lavage after Local Allergen Challenge of Asthmatic Airways

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Abstract
To assess the role of T lymphocytes in the initiation of the allergic asthmatic response we have investigated T-cells subsets and their activation markers in bronchoalveolar lavage (BAL) fluid recovered 10 min after local challenge of the bronchial mucosa with allergen or saline. Endobronchial challenge was performed in 13 mildly atopic asthmatic patients (FEV1% predicted range, 78.2 to 116.5) and 10 normal volunteers. In all of the asthmatics but in none of the normal subjects allergen but not saline exposure resulted in visible bronchoconstriction. Analysis of BAL by flow cytometry showed no differences in the overall number of T cells (CD3+) and their CD4+ and CD8+ subsets per milliliter of BAL between the groups of normal subjects and asthmatics. However, within 10 min of allergen challenge, in the asthmatics but not in the normal subjects, there occurred a significant loss of CD3+ cells (p < 0.01) comprising mostly CD4+ (p < 0.05) but also CD8+ cells, with a consequent decrease in the CD4:CD8 ratio. At this early time point no differences in the extent of expression of the T-cell activation markers, IL-2 receptor, and HLA-DR were found. These results provide evidence to support a role of T lymphocytes early in the allergen-induced inflammatory response in asthma.