title: Competition controls the rate of transition between the peripheral pools of CD4+CD25- and CD4+CD25+ T cells.
abstract: Recent reports have hinted that it is possible to regenerate CD4+CD25+ regulatory T cells (Treg) from CD4+CD25- cells, a phenomenon termed conversion. We evaluated the relative contribution of this process to the Treg pool by transferring purified populations of CD4+ T cells into T cell-deficient mice. We report that conversion of CD25- cells into the CD4+CD25+Treg pool is minor if other bona fide CD25+ Tregs are present. Moreover, in the same hosts, the loss of CD25 expression by a population of Tregs also decreases in the presence of co-injected CD4+CD25- cells. Thus, the rate of exchange between CD25- and CD25+ T-cell populations is determined by the presence or absence of T-cell competitors. Our results attest for the role of competition in the contribution of different T-cell subsets for the regeneration of the peripheral CD4+ T-cell pool during lymphopenia.
authors.affiliation: Lymphocyte Population Biology Unit, URA CNRS 1961, Institut Pasteur, 28 Rue du Dr. Roux, 75015 Paris, France.
authors.forename: Afonso R M
authors.initials: AR
authors.lastname: Almeida
authors.forename: Bruno
authors.initials: B
authors.lastname: Zaragoza
authors.forename: Antonio A
authors.initials: AA
authors.lastname: Freitas
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002469:Cell Separation / Q000379:methods; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D053645:Interleukin-2 Receptor alpha Subunit