IL5 and allergic disease: Alternatively, the lower capacity of neonatal T cells to express protein kinase C Ζeta (PKCζ) and a deficiency in PKC-dependent mitogen-activated protein kinases (MAPKs) cause dysregulation in T-cell division [59,60] and a greater tendency for the production of Th2 cytokines (IL-5, IL-13) [60], thus orchestrating a cascade of events favoring allergy development.