title: Human circulating group 2 innate lymphoid cells can express CD154 and promote IgE production.
abstract: BACKGROUND
  Protection against helminths consists of adaptive responses by TH2 cells and innate responses by group 2 innate lymphoid cells (ILC2s), with these latter being well characterized in mice but less so in human subjects.
  
  
  OBJECTIVE
  We sought to characterize human circulating ILC2s and compare their functional profile with that of autologous TH2 cells.
  
  
  METHODS
  Circulating ILC2s and TH2 cells were isolated by means of fluorescence-activated cell sorting and magnetic cell sorting and expanded in vitro. ILC2s were then stimulated with phorbol 12-myristate 13-acetate plus ionomycin, IL-25 plus IL-33 (IL-25/IL-33), or a mixture of Toll-like receptor ligands to evaluate their ability to produce cytokines, express CD154, and induce IgE production by autologous B cells. Cytokines and transcription factor gene methylation were assessed.
  
  
  RESULTS
  ILC2s expressed GATA-3, retinoic acid orphan receptor (RORC) 2, and RORα; were able to produce IL-5, IL-13, and IL-4; and, accordingly, were characterized by demethylation of IL4, IL13, IL5, GATA3, and RORC2, whereas the IFNG, IFNG promoter, and TBX21 regions of interest were methylated. ILC2s expressed TLR1, TLR4, and TLR6, and TLR stimulation induced IL-5 and IL-13 production. Moreover, ILC2s expressed CD154 in response to phorbol 12-myristate 13-acetate plus ionomycin, IL-25/IL-33, or a mixture of TLR ligands. Stimulated ILC2s also induced IgM, IgG, IgA, and IgE production by B cells. Finally, circulating ILC2s from atopic patients were not different in numbers and frequency but expressed higher IL-4 levels than those from nonatopic subjects.
  
  
  CONCLUSIONS
  This study provides the first evidence that human ILC2s can express CD154 and stimulate the production of IgE by B lymphocytes through IL-25/IL-33 stimulation or TLR triggering.
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy.
authors: Laura
authors: L
authors: Maggi
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy.
authors: Gianni
authors: G
authors: Montaini
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy.
authors: Alessio
authors: A
authors: Mazzoni
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy.
authors: Beatrice
authors: B
authors: Rossettini
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy.
authors: Manuela
authors: M
authors: Capone
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy.
authors: Maria Caterina
authors: MC
authors: Rossi
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy.
authors: Veronica
authors: V
authors: Santarlasci
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy; Regenerative Medicine Unit and Immunology and Cellular Therapy Unit of Azienda Ospedaliera Careggi, Florence, Italy.
authors: Francesco
authors: F
authors: Liotta
authors: Regenerative Medicine Unit and Immunology and Cellular Therapy Unit of Azienda Ospedaliera Careggi, Florence, Italy.
authors: Oliviero
authors: O
authors: Rossi
authors: Department of Surgery and Translational Medicine, University of Florence, Florence, Italy.
authors: Oreste
authors: O
authors: Gallo
authors: Department of Clinical & Experimental Medicine, Second University of Naples and Center for Biomolecular Studies Supporting Human Health, Second University of Naples, Naples, Italy.
authors: Raffaele
authors: R
authors: De Palma
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy; Regenerative Medicine Unit and Immunology and Cellular Therapy Unit of Azienda Ospedaliera Careggi, Florence, Italy.
authors: Enrico
authors: E
authors: Maggi
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy; Regenerative Medicine Unit and Immunology and Cellular Therapy Unit of Azienda Ospedaliera Careggi, Florence, Italy.
authors: Lorenzo
authors: L
authors: Cosmi
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy.
authors: Sergio
authors: S
authors: Romagnani
authors: Department of Experimental and Clinical Medicine and DENOTHE Center, Florence, Italy; Regenerative Medicine Unit and Immunology and Cellular Therapy Unit of Azienda Ospedaliera Careggi, Florence, Italy. Electronic address: francesco.annunziato@unifi.it.
authors: Francesco
authors: F
authors: Annunziato
mesh_terms: D000293:Adolescent; D000328:Adult; D023201:CD40 Ligand / Q000276:immunology*; D002452:Cell Count; D002460:Cell Line; D016207:Cytokines / Q000276:immunology*; D005260:Female; D050990:GATA3 Transcription Factor / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009298:Nasal Polyps / Q000276:immunology; D018168:Receptors, Retinoic Acid / Q000276:immunology; D051193:Toll-Like Receptors / Q000235:genetics / Q000276:immunology; D055815:Young Adult
chemical_list: D016207:Cytokines; D050990:GATA3 Transcription Factor; C494749:GATA3 protein, human; D018168:Receptors, Retinoic Acid; D051193:Toll-Like Receptors; D023201:CD40 Ligand; D007073:Immunoglobulin E
keywords: CD154; Group 2 innate lymphoid cell; IL-13; IL-4; IL-5; IgE; T(H)2; Toll-like receptor