IL5 and asthma: The numbers of both blood ILC2s and bronchoalveolar lavage fluid (BALF) ILC2s were shown to be increased in asthmatic mice, which contributed to the development of experimental asthma via the rapid secretion of IL-5 and IL-13 to aggravate lung eosinophilia and mucus production and exacerbate AHR (86, 87).