Jul 19, 1994

Engagement of the external domains of CD45 tyrosine phosphatase can regulate the differentiation of immature CD4+CD8+ thymocytes into mature T cells

Proceedings of the National Academy of Sciences of the United States of America
P BenvenisteA Singer


Immature precursor cells are induced in the thymus to express clonotypic T-cell antigen receptors (TCRs) and to differentiate into mature T cells. Perhaps the least understood event which occurs during intrathymic development is the positive selection of immature CD4+CD8+ thymocytes for differentiation into mature CD4+ and CD8+ T cells based on the TCR specificity individual thymocytes express. TCR expression by CD4+CD8+ thymocytes is quantitatively regulated by CD4-mediated activation of p56lck protein-tyrosine kinase whose activity can in turn be regulated by the membrane-bound protein-tyrosine-phosphatase CD45. Here we show that antibody engagement of CD45 external domains enhances Lck tyrosine kinase activity in CD4+CD8+ thymocytes, inhibits TCR expression, and inhibits differentiation of immature CD4+CD8+ thymocytes into mature T cells. Thus, engagement of the external domains of CD45 tyrosine phosphatase can regulate the ability of immature CD4+CD8+ thymocytes to undergo positive selection, suggesting an important regulatory role for intrathymic ligands that are capable of engaging CD45 within the thymus.

  • References3
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Mentioned in this Paper

Flow Cytometry
CD4 Antigens
Neoplasm of Uncertain or Unknown Behavior of Thymus
CD8 Antigens
Disease of Thymus Gland
PTPRC wt Allele

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