Monoclonal B-cell populations in aged IgH.TEμ mice express T antigen and CLL markers. (A) Quantitative RT-PCR analysis of large T antigen expression in RAN (▾, n = 5) and UNI (■, n = 16) purified splenic CD19⁺ B-cell fractions. Expression was normalized with HPRT, and relative expression in RAN B-cell fractions was set to 1. Each symbol represents an individual mouse; mean values are indicated by a line (*Significant difference with WT; P < .01; Mann-Whitney U test). (B) Western blot showing expression of large T protein (LT, arrow) in purified B-cell fractions from IgH.TEμ UNI mice. Numbers on the left indicate size in kDa. Examples are representative for 20 CLL samples analyzed. (C) Expression of CD19, IgM, IgD, CD5, and CD43 on BM, spleen, and lymph node cells from a IgH.TEμ UNI mouse. CD19⁺ cells were gated and analyzed for their IgM/IgD and CD5/CD43 profiles. Data are representative of 33 animals analyzed (for age of mice, see Table S1).