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Blood, 1 February 2008, Vol. 111, No. 3, pp. 1318-1326. Prepublished online as a Blood First Edition Paper on October 24, 2007; DOI 10.1182/blood-2007-08-106294. This Article Full Text Full Text (PDF) Supplemental Figure All Versions of this Article: blood-2007-08-106294v1 111/3/1318    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Hao, Q.-L. Articles by Crooks, G. M. Search for Related Content PubMed PubMed Citation Articles by Hao, Q.-L. Articles by Crooks, G. M. Related Collections Immunobiology Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  IMMUNOBIOLOGY Human intrathymic lineage commitment is marked by differential CD7 expression: identification of CD7– lympho-myeloid thymic progenitors Qian-Lin Hao1, Aswathi A. George1, Judy Zhu1, Lora Barsky1, Ewa Zielinska1, Xiuli Wang1, Mary Price1, Shundi Ge1, and Gay M. Crooks1 1 Division of Research Immunology/Bone Marrow Transplantation, Childrens Hospital Los Angeles, CA The identity and lineage potential of the cells that initiate thymopoiesis remain controversial. The goal of these studies was to determine, at a clonal level, the immunophenotype and differentiation pathways of the earliest progenitors in human thymus. Although the majority of human CD34+lin– thymocytes express high levels of CD7, closer analysis reveals that a continuum of CD7 expression exists, and 1% to 2% of progenitors are CD7–. CD34+lin– thymocytes were fractionated by CD7 expression and tested for lineage potential in B-lymphoid, T-lymphoid, and myeloid-erythroid conditions. Progressive restriction in lineage potential correlated with CD7 expression, that is, the CD7hi fraction produced T and NK cells but lacked B and myelo-erythroid potential, the CD7int (CD10+) fraction produced B, T, and NK cells, but lacked myelo-erythroid potential. The CD7– fraction produced all lymphoid and myelo-erythroid lineages and expressed HSC-associated genes. However, CD34+lin–CD7– thymocytes also expressed early T lymphoid genes Tdt, pT, and IL-7R and lacked engraftment capacity, suggesting the signals that direct lymphoid commitment and corresponding loss of HSC function are rapidly initiated on arrival of HSC in the human thymus. Thus, differential levels of CD7 identify the progressive stages of lineage commitment in human thymus, initiated from a primitive CD7– lympho-myeloid thymic progenitor. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

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