Multiparameter flow cytometric analysis of human fetal bone marrow B cells

Our results indicate a preponderance of immature phenotypes exist in the fetal BM B cell compartment. These immature cells can be grouped into three distinct populations, and probably correspond to expanded populations found less frequently in adult BM. This striking increase in the earliest identifiable stages of B cell ontogeny is consistent with an active expansion of cells destined to constitute the humoral immune system during fetal development