HUMAN T-CELLS, B-CELLS, NATURAL-KILLER, AND DENDRITIC CELLS ARISE FROM A COMMON BONE-MARROW PROGENITOR-CELL SUBSET

The early stages of lymphoid cell formation were studied by testing th e differentiative potential of phenotypically defined subsets of CD34( +) bone marrow cells, a subpopulation of CD34(+) Lin(-) CD45RA(+) cell s expressing CD10 was isolated by flow cytometry, Such cells are CD38( +), HLA-DR(+), do not express significant levels of Thy-1 and c-kit, l ack erythroid, myeloid, megakaryocytic potential, and give rise only t o lymphoid T, B, natural killer (NK), and dendritic cells (DC) in kine tics and titration experiments, Limiting dilution analysis demonstrate s the existence of multipotential B/NK/DC progenitor clones in the CD3 4(hi) Lin(-)CD10(+) adult bone marrow cell population, Thus, nonprimit ive progenitors for lymphoid cells and for DCs can be distinct from th ose of myeloid, megakaryocytic, and erythroid cells, implying that the DC lineage is developmentally more closely related to the lymphoid li neage than to the myeloid lineage, This study provides new insights in to the organization and development of the human lympho-hematopoietic system.