title: Phagocytosis of apoptotic neutrophils regulates granulopoiesis via IL-23 and IL-17.
abstract: Homeostatic regulation of neutrophil production is thought to match neutrophil elimination to maintain approximately constant numbers in the blood. Here, we show that IL-17, a cytokine that regulates granulopoiesis through G-CSF, is made by gammadelta T cells and unconventional alphabeta T cells. These neutrophil-regulatory T cells (Tn) are expanded in mice that lack leukocyte adhesion molecules, which have neutrophilia and defective neutrophil trafficking. Normal neutrophils migrate to tissues, where they become apoptotic and are phagocytosed by macrophages and dendritic cells. This curbs phagocyte secretion of IL-23, a cytokine controlling IL-17 production by Tn cells. Adoptive transfer of wild-type, but not adhesion molecule-deficient, neutrophils into mice deficient in beta2 integrins transiently decreases neutrophilia and reduces levels of serum IL-17. Antibody blockade of the p40 subunit of IL-23 reduces neutrophil numbers in wild-type mice. These findings identify a major homeostatic mechanism for the regulation of neutrophil production in vivo.
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Stark
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Huo
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Burcin
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Morris
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Olson
authors.forename: Klaus
authors.initials: K
authors.lastname: Ley
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D001853:Bone Marrow / Q000276:immunology; D018821:CD18 Antigens / Q000276:immunology / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000172:deficiency; D017690:Cell Transplantation; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology; D006098:Granulocytes / Q000276:immunology*; D020381:Interleukin-17 / Q000276:immunology* / Q000378:metabolism; D053759:Interleukin-23; D053760:Interleukin-23 Subunit p19; D007378:Interleukins / Q000276:immunology* / Q000378:metabolism; D008264:Macrophages / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D010587:Phagocytosis / Q000276:immunology*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism
chemical_list: D018821:CD18 Antigens; D015815:Cell Adhesion Molecules; C508841:Il23a protein, mouse; D020381:Interleukin-17; D053759:Interleukin-23; D053760:Interleukin-23 Subunit p19; D007378:Interleukins; D012333:RNA, Messenger