T-CELLS AND CYTOKINES IN BRONCHOALVEOLAR LAVAGE FLUID AFTER SEGMENTALALLERGEN PROVOCATION IN ATOPIC ASTHMA

Increasing evidence suggests a role for activated T cells and cytokine s in the regulation of eosinophilic inflammation in asthma. In this st udy, we investigated the distribution of leukocytes, lymphocytes, thei r activation state, and the cytokine profile in BAL from 10 atopic ast hmatics with positive skin prick tests and elevated specific IgE level s to birch or grass pollen. Using segmental allergen challenge, 250 PN U of the appropriate allergen or saline were instilled into different segments, which were lavaged 10 min (10 min) and 18 h (18 h) after all ergen challenge or 18 h after saline challenge (C). In peripheral bloo d the number of neutrophils and activated IL-2R+/CD4+ T cells increase d significantly 18 h after allergen provocation; there was no change i n eosinophils, other leukocytes, or lymphocyte subsets. In contrast, n umbers of eosinophils, neutrophils, and IL-2R+/CD4+ T cells increased significantly in BAL samples at 18 h. The numbers of neutrophils and e osinophils were not significantly different in the lavage performed at 10 min and at C. Analysis of cytokines in concentrated BAL fluid reve aled significantly increased levels of IL-5, IL-2, IL-1, TNF-alpha, IL -6, IL-8, and GM-CSF, but not of IL-4 and IFN-gamma at 18 h compared w ith those at C and at 10 min. The correlation between IL-5 levels, eos inophil numbers, and activated T cells supports a role for T-cell-deri ved IL-5 in causing tissue eosinophilia in allergic asthma.