Recruitment of circulating allergen-specific T lymphocytes to the lung on allergen challenge in asthma

Background: In allergic subjects with asthma, the migration of CD4(+) T cells to the lungs in the hours after allergen exposure may contribute to allergic inflammation in the target organ. Objective: We studied allergen-specific T cells from the peripheral blood and lungs of allergic subjects with asthma at baseline and after allergen challenge. Methods: In each patient, blood samples were taken 10 minutes before and 24 hours after the inhalation of a major sensitizing allergen. In vitro proliferation of peripheral blood CD4(+) T cells specific for the same allergen used in the in vivo challenge was assessed. In one patient two Dermatophagoides pteronyssinus-specific T-cell clones (TCCs) were derived from peripheral blood, and their T-cell receptors mere sequenced to determine their clonotypic determinants on the beta chains. The T-cell receptor determinants of the allergen-specific TCCs were sought in blood and bronchoalveolar lavage samples taken from this patient. Results: We found that allergen inhalation is followed by a decrement in the specific proliferation of peripheral CD4+ T cells to the same allergen used for bronchial provocation. In one patient the clonotypic determinants of two allergen-specific TCCs diminished in the peripheral blood, whereas they were simultaneously expanded in the lower respiratory tract. Conclusion: Our data suggest that allergen-specific T cells are recruited from the peripheral blood to the bronchial lumen after allergen challenge.