title: Commitment of common T/Natural killer (NK) progenitors to unipotent T and NK progenitors in the murine fetal thymus revealed by a single progenitor assay.
abstract: We have established a new clonal assay system that can evenly support the development of T and natural killer (NK) cells. With this system, we show that all T cell progenitors in the earliest CD44(+)CD25(-)FcgammaRII/III(-) fetal thymus (FT) cell population retain NK potential, and that the NK lineage-committed progenitors (p-NK) also exist in this population. T cell lineage-committed progenitors (p-T), which are unable to generate NK cells, first appear at the CD44(+)CD25(-) FcgammaRII/III(+) stage in day 12 FT. The proportion of p-T markedly increases during the transition from the CD44(+)CD25(-) stage to the CD44(+)CD25(+) stage in day 14 FT. On the other hand, p-NK preferentially increase in number at the CD44(+)CD25(-) stage between days 12 and 14 of gestation. The production of p-NK continues up to the CD44(+)CD25(+) stage, but ceases before the rearrangement of T cell receptor beta chain genes. It was further shown that the CD44(+)CD25(-) CD122(+) population of day 14 FT exclusively contains p-NK. These results indicate that the earliest T cell progenitor migrating into the FT is T/NK bipotent, and strongly suggest that the bipotent progenitor continuously produces p-NK and p-T until the CD44(+)CD25(+) stage.
authors.affiliation: Department of Immunology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ikawa
authors.forename: H
authors.initials: H
authors.lastname: Kawamoto
authors.forename: S
authors.initials: S
authors.lastname: Fujimoto
authors.forename: Y
authors.initials: Y
authors.lastname: Katsura
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D002454:Cell Differentiation / Q000187:drug effects / Q000276:immunology; D016207:Cytokines / Q000494:pharmacology*; D005333:Fetus; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000276:immunology*; D016130:Immunophenotyping; D007378:Interleukins / Q000494:pharmacology*; D007694:Killer Cells, Natural / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009924:Organ Culture Techniques; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000196:embryology* / Q000276:immunology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D016207:Cytokines; D007378:Interleukins; D011994:Recombinant Proteins