The role of innate lymphoid cells in alloimmunity
Innate lymphoid cells (ILCs) are a family of innate immune cells of lymphoid origin that regulate inflammation and adaptive immunity at mucosal and epithelial barriers. Over the course of the last decade, 3 major subtypes have been described: ILC1, ILC2, and ILC3. The ILC2 population has been shown to be protective against viral-induced lung inflammation, as well as participate augmentation of Th2 function, and proliferation of T regulatory cells in peripheral tissue and lymphoid organs. In addition, ILC2s have also been shown to expand innate immune suppressor cell populations such as myeloid-derived suppressor cells and are found in all solid organs that are currently transplanted including heart, kidney, and liver. Also, once thought to be solely tissue resident, recent evidence demonstrated that during inflammatory conditions, such as allergy, circulating ILC2s migrate into tissues to participate in Th2 responses. Preliminary data from our laboratory demonstrate that ILC2s participate in controlling alloimmune T cell infiltration. We also show that expansion of ILC2 via administration of IL-33 augments allograft survival. Despite the immunosuppressive activity of ILC2s, ILC2 activation alone is unable to fully constrain alloimmune responses and prevent rejection. Our lab is working on efforts to understand why and how we can augment this potent tissue resident innate immune cell population.