Analysis of myelopoiesis and B lymphopoiesis in transplanted NOD/SCID. (A) Overall distribution of myeloid (CD33⁺) and B-lymphoid (CD19⁺) lineages among human cells in spleen (n = 10), bone marrow (n = 50), and peripheral blood (n = 50). Differences between SPL and BM were significant (P < .05), differences between SPL and BM, and BM and PB were highly significant (P < .001). Bars indicate mean ± SEM. (B) Relative distribution of various myeloid and B-lymphoid subsets in the bone marrow of four representative animals (containing 84.5%, 76.6%, 78.9%, and 73.5% CD45⁺cells in the BM, respectively). Immature cells and monocytes both express HLA-DR⁺, whereas monocytes also express high levels of CD33. Granulocytes express CD33 but are negative for HLA-DR (left panel). All B cells express CD19 of which the most immature B cells lack both CD10 and CD20, with differentiation expression of CD10 is followed by expression of CD20 and, ultimately, loss of CD10 on the mature B cell (right panel). Animals included in this analysis had not been treated with a mobilizing regimen. Bars represent mean ± SEM (n = 4).