Figure 1.

Expression of Eμ-c-myc transgene results in impaired B cell development. (A) Bone marrow cells (Bm), splenocytes (Sp), or thymocytes (Th) were isolated from Eμ-c-myc and littermate control mice (LMC). Cells (4 × 10⁶) were lysed in sample buffer (see Materials and Methods) and proteins separated by SDS/PAGE. Samples were transferred to nitrocellulose membranes and protein visualized by probing blots with anti-c-Myc or anti-Max. (B) A model for characterizing B lymphocyte development utilizing monoclonal antibodies to surface markers and flow cytometry (modified from ref. 54). (C) Total bone marrow cells were stained with phycoerythrin (PE)-conjugated anti-B220 and FITC-conjugated anti-IgM. Total splenocytes were stained with FITC-conjugated anti-IgD and PE-conjugated anti-IgM. Cells were then visualized by flow cytometry, gated according to forward and side light scatter (lymphocyte gate), and staged according to a general scheme for B lymphocyte development as described by Hardy et al. (see diagram and ref. 54). The forward and side light-scatter gate excluded small apoptotic cells and granular cells, whereas large cells were included (Top). The expression of Eμ-c-myc transgene results in an increase in representation of pro-B and pre-B cells in the bone marrow (Bottom Left) and immature B cells in the spleen (Bottom Right) relative to littermate control mice.