Extensive Junctional Diversity of Ig Heavy Chain Rearrangements Generated in the Progeny of Single Fetal Multipotent Hematopoietic Cells in the Absence of Selection

摘要: We analyzed the progeny of individual multipotent hemopoietic cells, derived from para-aortic splanchopleura, earliest identified source lymphocyte precursors in pre-liver mouse embryos. Single were expanded an vitro culture system that permits both commitment and differentiation B cell precursors. show one single progenitor we could obtain large numbers rearrange Ig heavy chain genes generate a repertoire as diverse observed adult populations. N region additions are present at V(D)J junctions, showing terminal deoxynucleotidyl transferase expression has been switched on is not, consequently, intrinsic property stem cells. Throughout period, cells majority DJ vs rearrangements ratio 2:1 nonproductive to productive rearrangements, which close expected frequency absence selection. In addition, counterselection for D-J reading frame 2 joints, allelic exclusion was consistently observed. conclude three events associated with rearrangement, two them, namely D segment 2, cell, while selection induced bone marrow environment.