IL-27-induced PD-L1^highSca-1⁺ innate lymphoid cells suppress contact hypersensitivity in an IL-10-dependent manner

Innate lymphoid cells (ILCs) play an important role in maintaining tissue homeostasis and various inflammatory responses. ILCs are typically classified into three subsets, as is the case for T-cells. Recent studies have reported that IL-10-producing type 2 ILCs (ILC2₁₀s) have an immunoregulatory function dependent on IL-10. However, the surface markers of ILC2₁₀s and the role of ILC2₁₀s in contact hypersensitivity (CHS) are largely unknown. Our study revealed that splenic ILC2₁₀s are extensively included in PD-L1^highSca-1⁺ ILCs and that IL-27 amplifies the development of PD-L1^highSca-1⁺ ILCs and ILC2₁₀s. Adoptive transfer of PD-L1^highSca-1⁺ ILCs suppressed oxazolone-induced CHS in an IL-10-dependent manner Taken together, our results demonstrate that ILC2₁₀s are critical for the control of CHS and suggest that ILC2₁₀s can be used as target cells for the treatment of CHS.