Table 1.

Types of human innate lymphoid cells (ILCs) and their distinguishing features

ILC type	Sources of activation	Transcription factor	Subtypes	Effector molecules	Role in disease
ILC-1	IL-12 IL-15 IL-18	T-bet	Conventional NK cells CD103+ intraepithelial ILC (ieILC-1) CD127+	IFN-γ NK and ieILC-1: Granzyme Perforin	Immune response against intracellular pathogens and tumors Chronic gastrointestinal and pulmonary inflammation
ILC-2	IL-25 IL-33 TSLP	GATA3		Amphiregulin IL-4 IL-5 IL-9 IL-13	Immune response against helminths Driver of allergic disease and asthma
ILC-3	Aryl hydrocarbon receptor ligand IL-1 IL-6 IL-23	RORγt	Lymphoid tissue-inducer (LTi) NKp44+ T-bet + RORγt + double positive	IL-17 IL-22 LTi: LT-β TNF-α T-bet/RORγt+: IFN-γ	Immune response against extracellular pathogens Disease of gut and skin barrier, including inflammatory bowel disease and psoriasis

IFN interferon, IL interleukin, ILC innate lymphoid cell, LT-β lymphotoxin β, LTi lymphoid tissue-inducer, TNF-α tumor necrosis factor α, TSLP thymic stromal lymphopoietin