Leukemia development in Eμ-TCL1/IgHEL transgenic mice. Plots depict the percentage and absolute number of IgMa⁺ (filled circles) and IgMa⁻ (empty circles) B cells in the peripheral blood of (A) Eμ-TCL1/IgHEL transgenic mice that were not exposed to the HEL antigen (n = 14), (B) Eμ-TCL1/IgHEL transgenic mice repetitively immunized with HEL/CpG particles (n = 11), (C) Eμ-TCL1/IgHEL transgenic mice in which HEL was expressed as a soluble autoantigen (n = 9), and (D) Eμ-TCL1/IgHEL transgenic mice in which HEL was expressed as an intracellular autoantigen translocated on apoptotic cells (n = 10). (E) Flow cytometry analysis of representative leukemias stained with anti-IgMa, anti-IgMb, anti-CD19, and biotinylated HEL. Normal splenic B cells from an IgHEL transgenic mouse were used as a positive control for HEL binding.