Knockdown of HLA class I expression on MSCs does not change the course of KIR repertoire development. HSPCs from CB were differentiated on MSCs using shRNA-mediated β2M knockdown (B2M), empty vector control (empty), or no treatment (wt). The development of CD56⁺ NK cells (A) and the expression of KIR2DL1 (B), KIR2DL3 (C), and KIR3DL1 (D) were monitored by flow cytometry at the indicated time points. Mean values and standard deviations of 3 independent experiments are shown.