The role of IL-33/ST2L signals in the immune cells.

Interleukin (IL)-33 signals influence various immune cells during differentiation, immune responses and homeostasis. As discussed in this Review, IL-33 via TI/ST2L regulates the functions of immune cells including T cells, B cells, DCs, macrophages, mast cells, and innate lymphoid cells (ILCs). Stimulation with IL-33 is crucial for CD4+ T cell polarized into Th2 immunity and for the induction of Treg. CD8+ T cells can also express ST2L and IL-33 promotes features of effector CD8+ T cells. For macrophages and ILCs, ST2L presents on these cells and IL-33 induces Th2 cytokine production. IL-33 modulates adhesion, activation, maturation, and cytokine production by mast cells. ST2 is expressed in B1 and is important for differentiation of IL-10-producing B cells. Understanding the specific role of IL-33/ST2L in different immune cells will help to answer the remaining questions that are important for diseases pathologies and intervention strategies by targeting the IL-33/ST2L signals.