FIGURE 1.

Immature type 2 innate lymphoid cells (ILC2s), depending on the external stimulation, differentiate into i) pro‐allergic ILC2s (upon TSLP and IL‐33), or ii) IL‐10–producing ILC2s (upon IL‐7, IL‐33, and retinoic acid). Pro‐allergic ILC2s secrete IL‐5 and IL‐13, subsequently inducing Th2 responses. On the opposite, IL‐10⁺ ILC2 inhibit pro‐allergic, type 2 responses mediated by ILC2s and Th2 cells by secreting regulatory cytokine IL‐10 and increasing epithelial barrier integrity. Allergic patients undergoing allergen‐specific immunotherapy (AIT) present increased frequencies of IL‐10–producing ILC2s in the course of treatment. Furthermore, enhanced IL‐10⁺ ILC2s are related to decreased allergy symptoms severity. KLRG1, killer cell lectin‐like receptor subfamily G member 1; TSLP, thymic stromal lymphopoietin