title: An immune system switch at birth triggers a change in the lifespan of peripheral T cells.
abstract: Lymphocyte recirculation is an essential element in the integration of immune responses and is an absolute requirement for the development of systemic memory in postnatal animals. During foetal life a large pool of recirculating T cells develops and migration pathways of naive T cells to skin and peripheral tissues as well as LN are established. At birth a process is triggered whereby naive fetal T cells are rapidly lost from the circulating pool and are replaced by newly arriving T cells which have been formed since birth. At present our data suggest that the thymic export in the fetus creates a pool of long-lived naive T cells of wide diversity. The situation in neonatal lambs is more complex since the thymus is exporting large numbers of short-lived thymic emigrants which enter a peripheral T-cell population where many T cells are dividing.
authors.affiliation: Laboratory for Fetal and Neonatal Immunology, The University of Melbourne, Cnr Flemington Road and Park Drive, Parkville, Victoria, 3052, Australia.
authors.forename: R N
authors.initials: RN
authors.lastname: Cahill
authors.forename: W G
authors.initials: WG
authors.lastname: Kimpton
authors.forename: C P
authors.initials: CP
authors.lastname: Cunningham
authors.forename: E A
authors.initials: EA
authors.lastname: Washington
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002455:Cell Division; D002465:Cell Movement; D005260:Female; D008196:Lymph / Q000166:cytology / Q000276:immunology; D051379:Mice; D011247:Pregnancy; D012756:Sheep; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D013950:Thymus Gland / Q000196:embryology* / Q000254:growth & development*