IL4 and asthma: Asthma is characterized by AHR and chronic airway inflammation, which includes the infiltration of inflammatory cells into lung tissues, mucus overproduction, allergen-specific IgE, the over-expression of Th2-mediated cytokines, including interleukin (IL)-4, IL-5 and IL-13, and chemokines such as CCL11 (CCL11) and RANTES (CCL5).