Flicking the switch for B-cell development

The production of B cells is essential for a functional immune system. This process relies on the coordinated activity of a handful of transcription factors that act in part by modifying the chromatin landscape of lymphoid progenitors to allow the ordered expression of genes essential for B-cell development. In this issue of Genes & Development , Tingvall-Gustafsson and colleagues (doi:10.1101/gad.353002.125) have investigated the interplay of these transcriptional regulators with the chromatin state of developing lymphocytes at single-cell resolution. They pinpoint a rare population of progenitors where this epigenetic reprogramming occurs to simultaneously repress the expression of lineage-inappropriate genes and activate the B-cell program.