PDCD1 and asthma: In one study, a PD-1 agonist reduced lung ILC2s and ameliorated ILC2-mediated asthma; in this experiment, Rag2−/−Il2rg−/− mice were reconstituted with ILC2s from human peripheral blood, treated with the agonist, and then challenged intranasally with IL-33 or house dust mite or Alternaria extract138.