IL17A and asthma: Since CD45RO is a key marker for primed memory T cells19 and we observed that the circulating CD4+CD45RO+ILCs from asthma patients were more likely to express IL-17A than the corresponding CD4−CD45RO+ILCs or CD45RA+ILCs (Fig. 2h), we speculated that when asthma patients (but not healthy individuals) are exposed to cigarette smoke, the biological properties of ILC3s may change, including acquiring an activated memory-like phenotype (CD4+CD45RO+).