B-cell development in NOD/SCID/γ_c^nullmice that underwent transplantation with CB CD34⁺ cells. (A) Surface expressions of CD34, CD10, CD19, IgM, IgD, IgG, and IgA and intracellular expression of TdT were examined after setting a gate on the human CD45⁺population. (B) Human IgM, IgG, and IgA concentrations in plasma of NOD/SCID/γ_c^null and NOD/SCID-β2m^null mice that underwent transplantation with 4 × 10⁴ CB CD34⁺ cells were measured by ELISA.