Innate lymphoid cells: new paradigm in immunology of inflammation

Immune system is well characterized by immunologists into two major arms called innate immunity and adaptive immunity. However, recent advances in the field of immunology has led to the identification of specific immune cells, which lack signature signs of mature lymphocytes (i.e. antigen receptors), yet produce major cytokines (i.e. IFN-γ, IL-4, IL-5, IL-13, IL-9, etc.) of helper T (Th) cell mediated immune response. Therefore, these cells can be represented as the innate counterpart of helper T cells of adaptive immunity and are known as innate lymphoid cells (ILCs). These ILCs comprise of three different groups having different kinds of cells, i.e. group 1 (NK cells and ILC1 cells), group 2 and group 3 ILCs. However, they are also emerging as novel regulators of both chronic as well as acute inflammation induced by infection or caused by sterile inflammation. Therefore, an attempt has been made to highlight the regulatory role of ILCs during inflammation and modulation of these cells as novel tissue protective mechanism.