Figure 1. Human B lineage cells generated in humanized NOD-scid-IL2Rγ^null mice.

NOD-scid-IL2Rγ^null mice were engrafted with CD34⁺ stem cells obtained from human umbilical cord blood. Cells were recovered from bone marrow and spleen 16–18 weeks post-engraftment and examined by flow cytometry. (A) Total mononuclear cells isolated from the spleen (SPL) of a humanized NOD-scid-IL2Rγ^null mouse show the presence of 15% human CD45⁺ leukocytes in which CD19⁺ B lymphocytes comprise nearly one-fourth of the compartment. B cells were predominantly CD20⁺ CD38^int/lo and were chiefly IgD+ naïve cells (>90% on average in all three humanized mice). Results shown are representative of n = 3 humanized mice. (B) Figures depict the schemes used for sorting newly formed immature B cells (CD24^high CD38⁺ IgM⁺ IgD^–) in bone marrow (BM), and naïve B cells (CD19⁺ IgD⁺ CD27^–) in spleen. Boxes indicate the B cell compartments that were sorted for immunoglobulin gene sequencing.