CD4 and asthma: The involvement of Th2-type cytokines such as IL-4 and IL-5 was also reported to be important in the pathogenesis of asthma, and was found to shift the differentiation of naïve CD4+ T cells into Th2 cytokine-producing eosinophils and to promote eosinophil infiltration into the inflamed bronchial tree (22).