[Bipartite organization of human lymphopoiesis]

Due to difficulties to access primary bone marrow samples, human hematopoiesis has long remained far less characterized than in the mouse. Using an in vivo modeling approach of fetal hematopoiesis in humanized mice, we recently showed that human lymphoid cells stem from two functionally specialized populations of CD127^- and CD127⁺ early lymphoid progenitors (ELP) that differentiate independently, respond differently to growth factors, undergo divergent modes of lineage restriction and generate distinct lymphoid populations. Our results demonstrate that, conversely to the mouse, human lymphopoiesis displays a bipartite developmental architecture.