Fig. 7. PD-1 is inducible on human ILC2s and PD-1 agonist suppresses ILC2-mediated AHR.

a Human ILC2s were FACS-sorted from PBMCs as CD45⁺ lineage⁻ CD127⁺ CRTH2⁺. Purity was always ≥95%. b–d Cells were cultured (5 × 10⁴ per mL) in the presence of rh-IL-2 (10 ng mL⁻¹) and rh-IL-7 (20 ng mL⁻¹), with or without rh-IL-33 (20 ng mL⁻¹), PD-1 agonist (25 μg mL⁻¹), or corresponding isotype for 48 h. b Representative histogram of the expression of PD-1 in human ILC2s and corresponding quantification (right) presented as MFI; n = 4. c Levels of IL-5 and d IL-13 were quantified in culture supernatants from isotype- and PD-1 agonist-treated human ILC2s; n = 7. e–m In vitro cultured human ILC2s were adoptively transferred (intravenously) into Rag2^−/− Il2rg^−/− mice. At day 1, mice received an intraperitoneal injection of PD-1 agonist or control isotype (500μg). Then, mice were intranasally challenged with rh-IL-33 or PBS and injected with PD-1 agonist or isotype (250 μg) on days 2–4. Measurement of lung function and inflammation followed on day 5. f Lung resistance and g dynamic compliance measured in restrained tracheostomized mechanically ventilated mice exposed to increasing concentrations of methacholine; n = 4. h, i Total number of human ILC2s in lungs gated as CRTH2⁺ CD127⁺; n = 5. j Total number of eosinophils in BAL gated as CD45⁺ SiglecF⁺ CD11c⁻; n = 5. k Lung histology (Scale bars, 50 mm); representative of two independent experiments. l Quantification of airway epithelium thickness and m infiltrating cells; n = 6. Data are representative of at least two independent experiments and are presented as means ± SEM (two-tailed Student’s t test or one-way ANOVA). Mouse and human images provided with permission from Servier Medical Art.