CD4 and allergic asthma: The CD4+ T cell is a dominant activated T cell subtype in clinical allergic asthma and in animal models of asthma, an mainly contributes to AHR development and allergic inflammation by secreting Th2 cytokines such as IL-4, IL-5, and IL-13 (Serre et al., 2010; Raemdonck et al., 2016).