title: Age-related changes in the occurrence and characteristics of thymic CD4(+) CD25(+) T cells in mice.
abstract: Natural regulatory CD4(+) CD25(+) T cells play an important role in preventing autoimmunity by maintaining self-tolerance. They express CD25 constitutively and are produced in the thymus as a functionally mature T-cell population. Changes in the potential of these cells to regulate the activity of conventional effector lymphocytes may contribute to an increased susceptibility to infection, cancer and age-associated autoimmune diseases. In this study we demonstrated that the thymi of aged mice are populated by a higher percentage of CD4(+) CD25(+) thymocytes than in young animals. The expression of several surface markers (CD69, CD5, CD28, CTLA-4, CD122, FOXP3), usually used to characterize the phenotype of CD4(+) CD25(+) T regulatory cells, was compared between young and aged mice. We also examined the ability of sorted thymus-deriving regulatory T cells of young and aged BALB/c mice to inhibit the proliferation of lymph node lymphocytes activated in vitro. Natural regulatory T cells isolated from the thymi of young mice suppress the proliferation of responder lymph node cells. We demonstrated that thymus-deriving CD4(+) CD25(+) T cells of old mice maintain their potential to suppress the proliferation of activated responder lymphocytes of young mice. However, their potential to inhibit the proliferation of old responder T cells is abrogated. Differences in the occurrence and activity of CD4(+) CD25(+) thymocytes between young and old animals are discussed in relation to the expression of these surface markers.
authors.affiliation: Institute of Zoology, Department of Immunology, Warsaw University, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Kozlowska
authors.forename: Marzena
authors.initials: M
authors.lastname: Biernacka
authors.forename: Marzena
authors.initials: M
authors.lastname: Ciechomska
authors.forename: Nadzieja
authors.initials: N
authors.lastname: Drela
mesh_terms: D000375:Aging / Q000276:immunology*; D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D005260:Female; D016130:Immunophenotyping; D053645:Interleukin-2 Receptor alpha Subunit / Q000032:analysis; D051379:Mice; D008807:Mice, Inbred BALB C; D017634:Self Tolerance / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology*
chemical_list: D053645:Interleukin-2 Receptor alpha Subunit