Identification of pro-thymocytes in murine fetal blood: T lineage commitment can precede thymus colonization.

摘要: Phenotype and commitment of thymus-colonizing precursors are unknown. Here we report the identification T lineage-committed (designated prothymocytes) in murine fetal blood at day 15.5 development. Fetal pro-thymocytes Thy-1+c-kit(low)CD3- contrast to blood-derived pluripotent hematopoietic progenitors which Thy-1-c-kit+. Upon transfer into thymus, generate a single wave CD4+CD8+ thymocytes subsequently mature TCR alpha beta+ peripheral cells. However, lack multipotent progenitor potential since they fail reconstitute B lymphocytes myeloid erythroid lineages. In contrast, as well lineages reconstituted from progenitors. Pro-thymocytes equally present athymic mice, suggesting that this novel precursor population is prior thymus colonization represents earliest lineage identified.