Abnormal B-cell differentiation and pre-leukemia symptoms in MH knock-in mice. (A) FACS characterization of pre–pro-B cells, pro-B cells, pre-B cells, immature B cells, and mature B cells in the BM of WT and MH-Vav mice at 6 months. Left panel: statistical summary. Right panel, FACS analysis of BM cells. The B220+/IgMlow were pooled and subjected to further FACS analysis by using markers CD19 and CD43. (B) PB monitoring of 12-month MH mice. (C) FACS analysis of PB cells using markers B220, CD3, and Mac-1. (D) Visualization of immature cells in BM. Left panel, statistical summary. Right panel, morphologic visualization. (E-F) Abnormal differentiation in hematopoietic stem cells. Left panel, statistical summary. Right panel, FACS analysis with various cell markers (supplemental Table 10). (G) Lin–, B220+, CD3+, and Mac-1+ populations in BM. (H) FACS analysis of B-, T-, and myeloid lineages in BM using markers B220/CD43/CD19, CD4/CD8, and Mac-1/Gr-1, respectively. (I-K) Macro-anatomic examination of pre-leukemia status in 12-month MH mice. Comparisons of lymph nodes (I) and spleen (J-K) between WT and MH mice. (L) Hematoxylin and eosin (HE)-stained histopathologic sections of WT and MH spleens, in which the B cells were immunohistochemically stained by using the antibody against B220. (M) FACS analysis of MH spleen cells using markers B220, CD3, and Mac-1. (N) FACS analysis of B220+ spleen cells using markers CD19, CD43, IgM, IgD, CD21, and CD23. Data are presented as mean ± standard error of the mean and were analyzed by using the t test. *P < .05, **P < .01, ***P < .001. CLP, common lymphoid progenitor; Hgb, hemoglobin; LMPP, lymphoid-primed MPP; LRP, lineage-restricted progenitor; LT-HSC, long-term hematopoietic stem cell; SSC, side scatter; ST-HSC, short-term hematopoietic stem cell.