biostudies-literature00460Halim TYMedical Research CouncilWellcome TrustCanadian Institutes of Health Research57-64https://www.ebi.ac.uk/biostudies/studies/S-EPMC4685755biostudies-literatureUnknown17(1)Rapid activation of memory CD4(+) T helper 2 (TH2) cells during allergic inflammation requires their recruitment into the affected tissue. Here we demonstrate that group 2 innate lymphoid (ILC2) cells have a crucial role in memory TH2 cell responses, with targeted depletion of ILC2 cells profoundly impairing TH2 cell localization to the lungs and skin of sensitized mice after allergen re-challenge. ILC2-derived interleukin 13 (IL-13) is critical for eliciting production of the TH2 cell-attracting chemokine CCL17 by IRF4(+)CD11b(+)CD103(-) dendritic cells (DCs). Consequently, the sentinel function of DCs is contingent on ILC2 cells for the generation of an efficient memory TH2 cell response. These results elucidate a key innate mechanism in the regulation of the immune memory response to allergens.Nature immunologyGroup 2 innate lymphoid cells license dendritic cells to potentiate memory TH2 cell responses.PMC4685755UI05178805MC_U105178805100963/Z/13/Z100963Scanlon STMcKenzie ANZaghouani HHalim TYHwang YYGarbi NFallon PG46falseGroup 2 innate lymphoid cells license dendritic cells to potentiate memory TH2 cell responses.Rapid activation of memory CD4(+) T helper 2 (TH2) cells during allergic inflammation requires their recruitment into the affected tissue. Here we demonstrate that group 2 innate lymphoid (ILC2) cells have a crucial role in memory TH2 cell responses, with targeted depletion of ILC2 cells profoundly impairing TH2 cell localization to the lungs and skin of sensitized mice after allergen re-challenge. ILC2-derived interleukin 13 (IL-13) is critical for eliciting production of the TH2 cell-attracting chemokine CCL17 by IRF4(+)CD11b(+)CD103(-) dendritic cells (DCs). Consequently, the sentinel function of DCs is contingent on ILC2 cells for the generation of an efficient memory TH2 cell response. These results elucidate a key innate mechanism in the regulation of the immune memory response to allergens.2016-01-01T00:00:00Z2016 Jan2021-02-20T07:54:52Z2019-03-27T02:05:31ZS-EPMC46857552652386810.1038/ni.3294