Innate Lymphoid Cells: The Innate Counterpart to T Helper Cells.

Innate lymphoid cells (ILCs) are a recently discovered subset of innate immune cells that are capable of secreting great amounts of cytokines that have been found to influence effector cell activity. Chronic rhinosinusitis (CRS) in the absence (CRSsNP) or presence (CRSwNP) of nasal polyps has been characterized as type 1- and type 2-skewed, respectively, based on the presence of cytokines characteristic of type 1 and 2 immune responses. Based on the ability of type 1 ILCs to secrete interferon-x03B3;, a type 1 cytokine found elevated in CRSsNP and type 2 ILCs to secrete IL-5 and IL-13, type 2 cytokines found elevated in CRSwNP, it is essential to examine the role that ILCs may play in the pathogenesis of CRS. This chapter introduces each subset of ILC (type 1-3) and the non-CRS pathologies they have been associated with in both mouse and human models. It will discuss the current research into ILCs in CRS, particularly ILC2s and NK cells in CRSwNP. Finally, the chapter will consider the therapeutic implications of ILC involvement in CRS and highlight the needs for future research into the role that ILCs play in CRS.