title: Thymic regeneration: teaching an old immune system new tricks.
abstract: Recent studies in mice and humans show that the importance of the thymus extends well beyond the initial seeding of the peripheral T-cell pool. Although peripheral homeostasis can maintain T-cell numbers, the thymus is the major, if not the exclusive, source of new T-cell specificities. With age, thymus atrophy dramatically reduces the export of new T cells and predisposes an individual to impaired T-cell function, reduced T-cell immunity, and increased autoimmunity. Thymus atrophy is also the primary obstacle to restoration of the T-cell pool in the aftermath of HIV treatment or lymphoablative therapies. Here, we review thymus T-cell production, with particular attention to the factors that influence thymocyte export, and examine the impact that recent thymic emigrants have on the peripheral pool. In the future, thymic regeneration might become a feasible and potentially powerful approach to rejuvenating a depleted peripheral T-cell pool.
authors.affiliation: Section on Immunology and Immunogenetics, Joslin Diabetes Center, Brigham and Women's Hospital, Dept of Medicine, Harvard Medical School, 1 Joslin Place, Boston, MA 02215, USA. stuart.berzins@joslin.harvard.edu
authors.forename: Stuart P
authors.initials: SP
authors.lastname: Berzins
authors.forename: Adam P
authors.initials: AP
authors.lastname: Uldrich
authors.forename: Jayne S
authors.initials: JS
authors.lastname: Sutherland
authors.forename: Jason
authors.initials: J
authors.lastname: Gill
authors.forename: Jacques F A P
authors.initials: JF
authors.lastname: Miller
authors.forename: Dale I
authors.initials: DI
authors.lastname: Godfrey
authors.forename: Richard L
authors.initials: RL
authors.lastname: Boyd
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D019742:Chemokines, CC / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D007107:Immune System / Q000502:physiology*; D018448:Models, Immunological; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000378:metabolism; D012038:Regeneration / Q000502:physiology*; D013601:T-Lymphocytes / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology* / Q000502:physiology*
chemical_list: D019742:Chemokines, CC; D011948:Receptors, Antigen, T-Cell