OLIGOCLONALITY OF LUNG T-LYMPHOCYTES FOLLOWING EXPOSURE TO ALLERGEN IN ASTHMA

We were interested in studing the lung allergen-specific T cell repert oire in different conditions of allergen exposure in subjects with ato pic asthma, Twenty-one allergic individuals were studied: 17 subjects suffering mainly from asthma and 4 from rhinitis, They all performed s pirometry and methacholine challenge, All patients were subjected to b ronchoalveolar lavage (BAL), either at base line (no challenge) or aft er allergen or histamine challenge, and the TCR repertoire of their lu ng T cells was studied with heteroduplex analysis, Expansion of single T cell clones was observed in one (of seven) asthmatic subject that r eported a recent exposure to allergen and had high bronchial hypersens itivity to methacholine, and in seven/seven asthmatic subjects who und erwent BAL after they suffered an early asthmatic reaction to experime ntal allergen inhalation. Remarkably, ex vivo expanded clones included allergen-specific T cells, In two of the seven subjects who underwent BAL after allergen challenge, two different lung segments were lavage d. A strikingly symmetrical distribution of the expanded clones was fo und in these samples, Control subjects and six of seven asthmatic pati ents studied at base line showed polyclonality of lung 7 cells, In con clusion, T lymphocytes are clonally expanded in the lower respiratory tract only in asthmatic subjects exposed to allergen, These results su ggest that in allergic asthma, the inhalation of sensitizing allergens can recruit to the lung T lymphocytes that include allergen-specific T cell clones.