A Small CD11b+ Human B1 Cell Subpopulation Stimulates T Cells and Is Expanded in Lupus Investigators found two kinds of B1 cells that are distinguished by multiple surface markers and distinct transcriptomic profiles. In both umbilical cord and adult peripheral blood, a CD11b+ subset constitutes ~1 out of every 8-10 B1 cells, whereas a CD11b− subset constitutes the remaining B1 cells. [J Exp Med] Abstract