Allergic and Nonallergic Asthmatics Have Distinct Patterns of T-Cell Activation and Cytokine Production in Peripheral Blood and Bronchoalveolar Lavage

Activation of lymphocyte subpopulations was determined in conjunction with levels of cytokines in peripheral blood and bronchoalveolar lavage (BAL) of asthmatics. Allergic asthmatics had increased numbers of CD4+ IL-2R+ T cells in peripheral blood and BAL, and T-cell activation closely correlated with numbers of low-affinity IgE receptor (CD23) bearing B cells. In contrast, in nonallergic asthmatics both CD4+ and CD8+ T cells from blood and BAL had increased expression of IL-2R, HLA-DR, and VLA-1. Furthermore, in the nonallergic asthmatics CD8+ T cells were decreased in blood but increased in BAL. Cytokine levels were determined in BAL fluid and supernatants from purified peripheral blood T cells and enriched BAL lymphocyte preparations. Allergic asthmatics were characterized by increased levels of IL-4 and IL-5, and this elevated IL-4 contributed to the elevated IgE levels found in these allergic subjects. In contrast, nonallergic asthmatics had elevated levels of IL-2 and IL-5, with IL-2 contributing to T-cell activation. In both types of asthma, the close correlation of IL-5 levels with eosinophilia suggests that IL-5 is responsible for the characteristic eosinophilia of asthma. Thus, we provide evidence of distinct T-cell activation resulting in different spectra of cytokines in allergic and nonallergic asthma.