Page 582 - Veterinary Immunology, 10th Edition

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FIG. 19.2 The role of Group 1 innate lymphoid cells. Located in the
intestine, they are activated by IL-12 generated by dendritic cells.
They respond by producing type 1 cytokines and activating
macrophages. They can be considered the functional partners of
Th1 cells.

ILC1 cells can turn into ILC3 cells on exposure to IL-23, IL-1β,
and retinoic acid. Conversely, ILC3 cells may turn into ILC1 cells

under the influence of IL-12, IL-15 and IL-18. NK cells are closely
related to group 1 ILCs since they too produce IFN-γ and rely on
the T-bet transcription factor.

Group 2 ILCs

Group 2 ILCs are found in the lung, skin, bone marrow, liver,
mesenteric fat, and in the small intestine. They arise from lymphoid
stem cells and use two unique transcription factors, GATA-binding

protein-3 (GATA3) and retinoic acid receptor-related orphan
receptor-α (RORα). ILC2s produce large amounts of the Th2-
associated cytokines IL-5 and IL-13 and smaller amounts of IL-4,
and -9 in response to thymic stromal lymphopoietin (TSLP), IL-25,

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