CD4 and asthma: Asthma is classically considered an IgE-mediated, lymphocyte T helper 2 (Th2)-associated pathology, with an allergic inflammatory infiltrate characterized by eosinophils, mast cells, and CD4+ T cells producing interleukin-4 (IL-4), IL-5, and IL-13 in the airways (Martinez and Vercelli, 2013).