Basic characterization of transgenic mice. (A) H&E staining (left) and B220 immunohistochemistry of WT and EZH2^Y641F mice. (B) Spleen weights of mice transgenic for EZH2^Y641F and WT control mice analyzed at different ages. (C) Immunophenotypic analysis of bone marrow cells of EZH2^Y641F mice (n = 16) or WT controls (n = 13). (D) Immunophenotypic analysis of spleen cells of EZH2^Y641F mice (n = 7) or WT controls (n = 5). Means and standard deviation of the percentages of cells carrying the respective marker are shown. No significant differences were observed. (E) Immunophenotypic analysis of the GC B-cell compartment in the spleen of aged (60-62 weeks), nonimmunized EZH2^Y641F mice (n = 5) or WT controls (n = 5) using GL7 and FAS (upper) and CD38 and FAS (lower) (P = .003). Representative flow cytometric plots are shown to the right. Statistical analysis was performed using an unpaired Student t test with Welch’s correction. H&E, hematoxylin and eosin.