Figure 6. Cre-mediated deletion of the exogenous Bcl6 allele in precursor B-cells does not alter formation of mature B-cell malignancies.

a) Diagramatic representation of the Sca1-Bcl6Δ mice, showing expression of the transgenic Bcl6 allele within HSPCs under control of the Sca1 promoter, followed by Cre-mediated deletion at an early Pro-B cell stage upon Mb1 expression. b) Southern blot analysis confirms absence of the transgenic Bcl6 allele within mature (B220+) B-cells of Sca1-Bcl6^Δ mice. Image is representative of 3 replicate experiments. c) Lymphoma-specific survival of Sca1-Bcl6^Δ mice (n=13) demonstrates a significantly (Log-rank P-value <0.001) shorter lifespan compared to wild-type mice (n=20). d) Example of splenomegaly observed in Sca1-Bcl6^Δ mice, with spleen from a wild-type mouse is shown for reference. Images are representative of 13 mice. e) Effacement of spleen (100×, inset 400×) by malignant B-cells and infiltrates in the liver (200×) and bone marrow (left 200×, right 400×) result in loss of normal architecture. Images representative are of 13 mice. Scale bar represents 200µm.