Activated Notch1 promotes differentiation of early lymphoid precursor cells and blocks B-cell differentiation.

Flow cytometric analysis of the bone marrow of competitive repopulated mice 2 months after transplantation of Sca1⁺lin⁻ RAG-1^−/− cells expressing activated Notch1 (MSCV-ICN/GFP) or control vector (MSCV-GFP). (A) Plots represent fluorescence intensity for CD43 on the x-axis and CD24 on the y-axis in the B220⁺GFP⁺cell population of the bone marrow of 2 representative animals. Numbers in corners represent percent of events within that quadrant, gated on GFP⁺B220⁺ lymphoid cells. (B) Plots represent fluorescence intensity for B220 on the x-axis and CD19, BP-1, CD25, or NK1.1 on the y-axis in GFP⁺Ly5.2⁺ bone marrow cells. Numbers in corners represent percent of events within that quadrant, gated on GFP⁺Ly5.2⁺ lymphoid cells. (C) Flow cytometric analysis of the bone marrow of competitive transplanted animals 2 months after transplantation of Sca1⁺lin⁻ RAG-1^−/− cells expressing activated Notch1 or control vector. Chart represents the average percentage ± SEM of B220⁺CD19⁺and B220⁺NK1.1⁺ bone marrow cells in the GFP⁺Ly5.2⁺ population. The Student ttest was used to analyze the data. (B220⁺CD19⁺,P = .01; B220⁺NK1.1⁺,P = .002). (D) Plots represent fluorescence intensity for CD44 on the x-axis and CD25 on the y-axis in the GFP⁺Ly5.2⁺ cell population of the bone marrow of 2 representative competitive repopulated animals 5 months after transplantation. Numbers in corners represent percent of events within that quadrant. Chart shows the average percentage ± SEM of CD25⁺CD44⁺ cells in the GFP⁺Ly5.2⁺ bone marrow population in primary recipients. The Student t test was used to analyze the data (P = .01).