Innate Lymphoid Cells

Abstract

Innate lymphoid cells (ILCs) are white blood cells derived from a common progenitor in the bone marrow. They respond rapidly to a limited array of antigens at the site of infection to provide immediate protection. The first identified ILCs were natural killer cells. However, several non‐cytotoxic members of the family have since been reported. All ILCs lack the rearranged antigen receptors characteristic of T‐ and B‐cells but can be similarly divided into three main groups based on cell surface markers and cytokine expression profiles. Similar to their adaptive immune response counterparts, they play specific roles in providing host defence against different pathogens. In addition, there is growing evidence that ILCs can contribute to multiple inflammatory and autoimmune diseases. Key Concepts ILCs are lymphocytes of the innate immune system and provide a rapid response to invading pathogens. ILCs lack the specific antigen receptors found on cells of the adaptive immune system. Development of ILCs is governed by sequential expression of different transcription factors and proceeds from a common precursor found in the bone marrow. Differential expression of cell surface markers and cytokines allows ILCs to be grouped into three families, each having a different role in host immunity. ILCs respond to signals released from epithelial and other cells to provide a rapid source of cytokines that can recruit other immune cells and stimulate tissue repair. The dysregulation of ILC activation has been linked to several human inflammatory and autoimmune diseases.