Single UCB primitive progenitors give rise to polyclonal NK cells.

(A-E) These panels (gated on a lymphocyte window) show progeny of single UCB CD34⁺/Lin⁻/CD38⁻ cells cultured on AFT024 with FL, KL, IL-3, IL-7, and IL-2 and then stained with antibodies for each of the individual KIR receptors as indicated. Panels A-C were derived from the same single cell with class I HLA type: A1, A2, B8, B62,15 Bw6, Bw6, Cw7, and Cw3 (lacks ligand for NKB1 and CD158a). Panels D and F were from nontyped donors, showing representative NKB1 and CD158a staining patterns. Panel F shows single cell progeny (gated on CD56⁺ cells), showing the coexpression of CD94 and NKG2A. This example was chosen to show the CD94⁺/NKG2A⁻ population, although most NK cell progeny derived from a single cell showed less CD94⁺/NKG2A⁻ cells. Panel G demonstrates single cell progeny (gated on CD56⁺ cells), showing the coexpression of CD94 and a KIR cocktail of the 3 known antibodies. This example was chosen to highlight the CD94⁻/KIR⁺population, although most NK cell progeny derived from a single cell showed less CD94⁻/KIR⁺ cells. Panel H shows the progeny of a 4-week secondary culture initiated with CD158b⁺/NKB1⁻ cells after 42 days of primary culture-initiated UCB CD34⁺/Lin⁻/CD38⁻ cells. This example shows that CD158b expression was stable and new KIRs were acquired in secondary culture. Panel I (gated on CD56⁺cells) shows the expression of KIR3DL1 (NKB1) and KIR2DL2/L3/S2 (CD158b) from a single UCB primitive progenitor. The UCB used for this example showed the following class I HLA type: A1, A3, B35, B35, Bw6, Bw6, and Cw4 (lacks ligand for NKB1 and CD158b). This example also shows the polyclonal nature of KIR acquisition and the expression of one or 2 specific KIRs on each NK cell.