CD4 and asthma: In terms of neuroimmune interactions, IL‐5 from ILC2 and CD4+ T cells directly stimulates VIP secretion from pulmonary nociceptors, and VIP in turn activates ILC2 and CD4+ T cells, forming a positive feedback loop that amplifies Type 2 inflammation in OVA‐ and HDM‐induced asthma mouse models [692].