Читать книгу Immunology - Richard Coico - Страница 49

Innate lymphoid cells (ILCs) constitute a heterogeneous family of innate immune cells also derived from common lymphoid progenitors. Currently, ILCs are divided into three functionally distinct groups (ILC1, ILC2, and ILC3) based upon the cytokines they produce (Table 2.3). The first ILCs to be characterized were those defined as NK cells which are now defined as members of the ILC1 group. Not to be confused with the small population of CD4⁺ NKT cells that express CD4 as described above. NK cells are large granular lymphocytes. They contain intracellular granules with preformed biologically potent molecules that are released when NK cells make contact with target cells. Some of these molecules cause the formation of pores in the membrane of the target cell, leading to its lysis (see Chapter 3). Other molecules enter the target cell and cause apoptosis (programmed cell death) of the target cell by enhanced fragmentation of its nuclear DNA. Hence, they are able to lyse certain virus‐infected cells and tumor cells without prior stimulation. A more detailed discussion regarding the role of ILCs in innate immune responses is given in Chapter 3 but it is noteworthy that our understanding of this population of immune cells is still in its infancy.