High altitude climate therapy reduces peripheral blood T lymphocyte activation, eosinophilia, and bronchial obstruction in children with house-dust mite allergic asthma.

Asthma is a multifactorial disease of unknown etiology but often associated with atopy and inflammation. Previous studies in adult asthma have demonstrated the presence of activated T cells in blood, bronchoalveolar lavage (BAL) fluid, and bronchial tissue, and the relevance of their soluble products for eosinophil function. In view of these observations, it was hypothesized that similar pathogenetic mechanisms also occur in childhood asthma. In fact, peripheral blood T lymphocytes in 14 children with house-dust mite allergic asthma showed clear evidence of T cell activation as measured by the expression of CD25 and HLA-DR antigen. Without changing medication, significant reduction of the IL-2 receptor alpha-chain expression within the CD4+ lymphocyte population was observed after only 3 weeks of allergen avoidance. Within this time period, absolute and relative eosinophil numbers decreased to normal levels. After 5 weeks in an area of low house-dust mite exposure, lung function also presented evidence for clinical improvement of the asthmatic disease. These results indicate similar pathogenetic mechanisms in childhood and adult asthma. Furthermore, they suggest that allergen avoidance may contribute to the efficient therapy of asthma in patients with house-dust mite IgE-meditated allergy.