STAT6 expression in T cells, alveolar macrophages and bronchial biopsies of normal and asthmatic subjects

We have investigated the expression of STAT6 in peripheral blood T-lymphocytes, alveolar macrophages and bronchial biopsies from 17 normal subjects and 18 mild-moderate steroid-na？ve stable asthmatic patients.STAT6 expression was variable and was detected in T-lymphocytes, macrophages and bronchial epithelial cells from all subjects with no difference between normal and stable asthmatic subjects.STAT6 expression in different cells suggests that it may be important in regulating the expression of not only Th2-like cytokines in T cells of man, but may also regulate STAT-inducible genes in alveolar macrophages and airway epithelial cells.Asthma is characterised by chronic airway inflammation, with infiltration of T-lymphocytes, mast cells, eosinophils and monocytes/macrophages. This is associated with the increased expression of several inflammatory proteins, including cytokines, enzymes, receptors and adhesion molecules [1]. The molecular pathways involved in the induction of chronic cytokine expression and recruitment to the airways and activation of inflammatory cells in asthma are not well understood. However, there is increasing recognition that these processes involve increased transcription of inflammatory genes, and that this is regulated by transcription factors [1]. Several transcription factors are involved in asthmatic inflammation including nuclear factor-κB (NF-κB) [2,3] and activator protein-1 (AP-1) [4].CD4+ T helper (Th) cells can be divided into four major subsets termed Th1, Th2, Th17 and Th0 based on the pattern of cytokines they produce. More recently, another two subsets of effector CD4+ Th cells, named Th9 and Th22 cells, have been described, even if their pathophysiological meaning is still unclear [5,6]. Th1 cells produce predominantly interferon gamma (IFNγ) and predominantly promote cell-mediated immune responses, whereas Th2 cells, which produce mainly IL-4, IL-5 and IL-13, provide help for some B cell responses. IL-4 and IL-13 in particular