HEMATOPOIETIC ORIGIN OF HUMAN NATURAL-KILLER (NK) CELLS - GENERATION FROM IMMATURE PROGENITORS

Human natural killer (NK) cells originate from bone marrow, but little is known about NK cell progenitors and ontogeny. We studied the pheno type and functional activity of NK cells derived from highly purified human bone Human natural killer (NK) cells originate from bone marrow, but little is marrow CD34+ cells, which exhibited neither lyric activ ity nor expression of surface antigens characteristic of NK (CD56) or T (CD3) cells. However, when cultured with hematopoietic growth factor s or feeder layers for up to 4 weeks, up to 86% functional CD56+ cells were seen in the absence of mature T cell development. CD56+ cells ap peared in all cultures at 2 or 3 weeks, with the largest percentage in those exposed to IL-2. These studies demonstrated that NK cells arise 'in vitro' from immature bone marrow progenitors and also suggest a s eparate origin and differentiation pathway for NK and T cells.