ICOS and Hermansky-Pudlak syndrome: In order to determine what cytokines and growth factors released from ILC2s contribute to the development of lung fibrosis in HPS, we sorted Lineage– (CD3–CD11b–CD45R/B220–Ly76–Ly6G–Ly6C–), Thy1.2+ICOS+T1/ST2+ ILC2s and examined the gene expression by real-time PCR and RNA-Seq.