T cell receptor-gamma, delta-expressing fetal mouse thymocytes are generated without T cell receptor V beta selection.
We investigated whether fetal mouse T cell receptor (TCR) gamma delta cells have been subjected to so-called TCR beta selection at the CD25 stage of thymus development. To this end, we carried out a comparative three-color flow microfluorimetric analysis to TCR gamma delta cells developing in the fetal, neonatal and adult thymus using monoclonal antibodies to CD2, CD8, CD24, CD25 and CD44. Day-15 fetal TCR gamma delta cells were CD2+ suggesting an origin at a post-CD25 stage. Molecular analysis of TCR beta rearrangements were also carried out. Thus, by semi-quantitative polymerase chain reaction (PCR) amplification of V beta 6 and V beta 8 to J beta 2 rearrangements day-15 fetal TCR gamma delta showed extensive TCR beta rearrangements, a finding confirmed by PCR amplification from single micromanipulated cells. Finally, sequencing analysis of 104 PCR-amplified TCR VDJ beta 2 fragments showed that the majority (58%) were rearranged out of frame . Taken together, these phenotypic and molecular analyses suggest that fetal TCR gamma delta cells have not been subject to TCR beta selection.
Mertsching
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E
U 184 INSERM, Faculté de Médecine, Strasbourg, France.
Ceredig
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R
D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D002454:Cell Differentiation; D017637:Clonal Deletion; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000235:genetics*; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology / Q000196:embryology / Q000254:growth & development
D016692:Receptors, Antigen, T-Cell, gamma-delta