Absolute cell counts for the main white blood cell populations. Flow cytometry was performed on whole blood with counting beads to determine the number of cells /mL for (A) monocytes (CD14+), (B) granulocytes (FSC/SSC), (C) T cells (CD3+), (D) B cells (CD19+), (E) NK cells (CD56++ and CD56+/16+), (F) NKT cells (CD3+ CD56+), (G) Myeloid dendritic cells (HLA‐DR+ CD19‐ CD1c+ CD11c+), and (H) plasmacytoid dendritic cells (PDC: HLA‐DR+ CD123+ CD304+). The Y‐axes are 106 cells/mL for A‐E, 104 cells/mL for F, and 103 cells/mL for G‐H and the X‐axes are months after transplant. The ‘>18’ group includes eight patients sampled at 18‐36 months. Values for umbilical cord blood (C) and adult peripheral blood (A) controls are provided for reference. The FACS files for outlying samples were reanalysed for confirmation. Horizontal bars represent means with standard error. Key: The boxes below the plots represent t‐test comparisons against the values for UCB (upper row) and AB (bottom row): white P > 0.5; grey P ≤ .05; black P ≤ .005. UCB and AB differed significantly (P < .05) for cell types in (A‐E). Further statistical information in Table S1