IL4 and asthma: Further evidence referring to the very important roles played by IL-4 and IL-13 in asthma pathobiology ensues from the copious quantities of these cytokines which can be found in bronchial mucosa, induced sputum, bronchoalveolar lavage (BAL) fluid, and peripheral blood from asthmatic patients (Saha et al., 2008; Maes et al., 2012; Corren, 2013).