Generation of human natural killer cells from peripheral blood CD34⁺ cells mobilized by granulocyte colony-stimulating factor

We studied the generation of human natural killer (NK) cells from CD34⁺ cells that were isolated from peripheral blood stem cells (PBSC) mobilized by granulocyte colony-stimulating factor (G-CSF). The isolated CD34⁺ cells were cultured in the presence of a combination of interleukin-1 (IL-1α), IL-2, and stem cell factor for 5 weeks without marrow stroma. We found that the CD34⁺ cells isolated from G-CSF-mobilized PBSC (G-CSF/PBSC) could differentiate into a population of NK cells which were CD56⁺((bright))/CD3^- and showed morphologic characteristics of large granular lymphocytes. Immunophenotypic analysis of the NK cells thus generated showed that a small proportion of them expressed CD2, CD8 and CD16 surface markers and approximately half of them coexpressed CD7. This NK population exhibited cytotoxic activity against a NK-sensitive cell line, K562. These observations suggest that CD34⁺ cells from G-CSF/PBSC contain precursors of NK cells that can differentiate into functional NK cells.