title: Origin and development of the gamma delta T-cell system in sheep: a critical role for the thymus in the generation of TcR diversity and tissue tropism.
abstract: Ruminant gamma delta T cells are concentrated at epithelial surfaces and share many features in common with species such as mice and humans which contain relatively fewer gamma delta T cells than ruminants. To date no gamma delta T cells with invariant TcR have been found in sheep and the generation of gamma delta TcR diversity which is thymic dependent follows a developmentally regulated sequence. Analysis of thymic export of gamma delta T cells shows that emigration of gamma delta T-cell subsets increases markedly during fetal life and after birth suggesting intrathymic processes leading to mature gamma delta T cells may change during development. Skin homing gamma delta T cells acquire their tissue tropism inside the thymus and pathways of recirculation of gamma delta T cells to skin are laid down during fetal development independent of antigen and remain stable through into adult life.
authors.affiliation: Laboratory for Foetal and Neonatal Immunology, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: R N
authors.initials: RN
authors.lastname: Cahill
authors.forename: W G
authors.initials: WG
authors.lastname: Kimpton
authors.forename: E A
authors.initials: EA
authors.lastname: Washington
authors.forename: I D
authors.initials: ID
authors.lastname: Walker
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000276:immunology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000096:biosynthesis* / Q000502:physiology*; D012756:Sheep; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology / Q000502:physiology*
chemical_list: D016692:Receptors, Antigen, T-Cell, gamma-delta