Inflammatory and T-cell profile of asthmatic airways 6 hours after local allergen provocation

T cells in the airways are considered to play a key role in orchestrating the inflammatory response of asthma through the elaboration of specific cytokines. Using flow cytometry we have investigated the T-cell response of sensitized asthmatic airways 6 h after local allergen provocation. Twelve subjects with atopic asthma underwent bronchoalveolar lavage (BAL) before and 6 h after local instillation of allergen into the right middle robe (RML) and saline into the right upper lobe (RUL). Allergen challenge produced a significant 26% fall in FEV(1), an increase in eosinophils in BAL at 6 h, and at 24 h an increase in methacholine responsiveness compatible with late-phase airway inflammation. When compared with saline challenge, allergen produced an overall decrease in the number of BAL lymphocytes from 21.3 +/- 2.8% to 16.0 +/- 3.08% of total cells but no change in the proportion of CD4(+), CD8(+), CD25(+), or HLA-DR(+) cells. Allergen provocation reduced the proportion of T cells expressing the beta(2) integrin lymphocyte functional antigen-1 (LFA-1) from 72.5 +/- 30 to 43.9 +/- 9.1 mean fluorescent units (p < 0.01) and a similar trend in intercellular adhesion molecule-1 (ICAM-1) (p = 0.08). These results indicate that late-phase inflammatory events 6 h after local allergen provocation involve the selective retention of airway T cells expressing specific cell adhesion molecules.