Since the initial studies of the roles of T cells in the pathogenesis of asthma [4], [5], our understanding of the CD4+ T lymphocyte in the immunopathology of this disease has greatly advanced over the past decades, involving not only the classic Th1 and Th2 cells, but also new proinflammatory and suppressive T-cell subsets [6]. The gene discussed is CD4; the disease is asthma.