Figure 3. Regulation of adaptive immunity by ILCs.

ILCs regulate T cells both directly through antigen presentation on MHC II, and indirectly through the regulation of DCs. The crosstalk between ILCs, DCs and T cells establishes a complex regulatory network, involving positive and negative feedbacks, the dynamics of which remain to be elucidated. The mechanisms by which ILCs repress CD4⁺ T helper (Th) cell activation remain unclear, but may involve the lack of costimulatory molecules in the context of steady-state (84). It also remains unclear how DCs negatively regulate the activity of ILCs (57). Red lines depict feedback loops, and A, B and C list the type 1, type 2 or type 3 cytokines involved in a specific crosstalk. ILC3s also activate B cells in the intestine through lymphotoxin-mediated recruitment of T helper cells and activation of dendritic cells (91), as well as marginal zone B cells in the spleen (132).