Lymphocyte activation in bronchoalveolar lavage and peripheral blood in atopic asthma.

To study the role of T lymphocytes in atopic asthma we have examined cell populations in peripheral blood and bronchoalveolar lavage (BAL) from 12 atopic asthmatics and 10 healthy volunteers using flow cytometry and a panel of monoclonal antibodies directed toward T-cell surface antigens. BAL from asthmatics contained more eosinophils (mean, 0.54 +/- 11.2 x 10(6) versus 0.06 +/- 0.08 x 10(6) absolute count, p less than 0.05), but no greater total or percent of T lymphocytes. There was no difference between the two groups in the relative numbers of CD4+ or CD8+ T cells. However, there was a significant increase in the mean number of BAL CD3+ lymphocytes expressing the activation markers interleukin-2 receptor (IL-2R, CD25) (8.48 versus 4.37%, p less than 0.01) and human lymphocyte antigen-DR (11.08 versus 7.74%, p less than 0.05) in the asthmatics. In contrast to lavage cells, there was no difference in CD3+ cell activation markers in the peripheral blood. These findings suggest that T-lymphocyte activation occurs within the airways in symptomatic atopic asthma.