Interferon-γ inhibits the growth of human bronchial epithelial cells independently of transforming growth factor-β-1 and nitric oxide (NO)

It has been emphasized that epithelial injury is closely correlated with airway hyperresponsiveness, which is one of the important pathophysiological characteristics of bronchial asthma. Growth of epithelial cells is important in the mucosal repair processes and is believed to be regulated by growth factors produced by inflammatory and immune effector cells as well as epithelial cells themselves. We studied the role of T cell-derived lymphokines IFNγ and IL-4 on the proliferation of human bronchial epithelial cell line BEAS-2B, IFNγ, but not IL-4, showed a dose-dependent growth inhibitory activity in vitro. Its activity was via its specific receptors on the cells, was augmented by TNFα, and was independent of the activity of endogenous TGFβ and nitric oxide. These results suggested that Th-1 T cells-derived lymphokine IFNγ might be involved in the repair processes after mucosal injury found in bronchial asthma.