Fig. 1.

A schematic representation of the NK cells development and division in human BM and thymus. Briefly, in the BM stroma, human CD34⁺/CD135⁺ HSCs differentiate into CD34⁺/CD44⁺ CLPCs under the stimulation of SCF, IL-7, and IL-17. Inside the BM, CLPCs directly generate CD34⁺/IL2/15Rβ⁺/15Rα⁺ NK cells precursors. CD19⁺ B cells are also generated indirectly from the CLPCs in the BM. Unlikely, inside the thymus, the CLPCs transition to CD34⁺/IL2/15Rβ⁺/15Rα⁺ NK cells precursors is indirectly occurred through differentiation of the CD34⁺/CD44⁺ CLPCs to CD2⁺/CD25⁺ pro-T cells. Besides the generation of NK cells precursors, all of the CD3⁺ T cell lineages are produced within the differentiation of CD2⁺/CD25⁺ pro-T cells in the thymus. Finally, under the stimulation with IL-2 and IL-17, the mature CD16⁺/CD56⁺/CD3⁻ NK cells are generated through CD34⁺/IL2/15Rβ⁺/15Rα⁺ NK cells precursors differentiation in both BM stroma and thymus. Below each cell, lineage-specific markers are shown. For more details, please refer to the text