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 (ILC2(10)s) have an immunoregulatory function dependent on IL-10. However, the surface markers of ILC2(10)s and the role of ILC2(10)s in contact hypersensitivity (CHS) are largely unknown. Our study revealed that splenic ILC2(10)s are extensively included in PD-L1(high)Sca-1(+) ILCs and that IL-27 amplifies the development of PD-L1(high)Sca-1+ ILCs and ILC210s. Adoptive transfer of PD-L1(high)Sca-1(+) ILCs suppressed oxazolone-induced CHS in an IL-10-dependent manner Taken together, our results demonstrate that ILC2(10)s are critical for the control of CHS and suggest that ILC2(10)s can be used as target cells for the treatment of CHS.