T cell cytokine profiles in childhood asthma

Abstract

Background: An imbalance of T cell subsets in asthma with a predominance of Th2 type cells has been proposed. The aim of this study was simultaneously to detect surface markers and intracellular production of cytokines in T cells from the airways of children with and without asthma. Methods: Bronchoalveolar lavage (BAL) fluid was obtained by wedging a suction catheter into the distal airway immediately before elective surgery. Cells were stimulated with phorbol 12-myristrate 13-acetate (PMA) and ionomycin and intracytoplasmic cytokine retention was achieved using monensin. The cells were stained with the relevant antibodies and analysed by flow cytometry. Results: No statistical difference was observed between children with atopic asthma, atopic non-asthmatic subjects, and normal controls in the percentage of CD3+ cells producing interleukin (IL)-2 or IL-4. Interferon (IFN)γ+ T cells were, however, present in a much higher percentage than either IL-2 or IL-4 positive cells. The percentage of IFNγ+ T cells was significantly increased in subjects with atopic asthma (median 71.3%, interquartile range (IQR) 65.1-82.2, n=13) compared with both atopic non-asthmatic subjects (51.9%, IQR 37.2-70.3, n=12), p<0.05 and normal controls (58.1%, IQR 36.1-66.1, n=23), p<0.01. Conclusions: These findings indicate that IFNγ producing T cells are more abundant in the airways of children with atopic asthma than in atopic non-asthmatic subjects and controls. The proinflammatory activities of IFNγ may play an important role in the pathogenesis of childhood asthma and may suggest that asthma is not simply a Th2 driven response.