CD19 and B-cell chronic lymphocytic leukemia: To ascertain the differences in CD19 and IgM expression between MCL and chronic lymphocytic leukemia, analysis of chronic lymphocytic leukemia sample (pt8) revealed an abundance of the four subclones, namely in the descending order, CD19−/IgM−, CD19+/IgM−, CD19−/IgM+, CD19+/IgM+, and CD19+/IgM− cells, compared with normal and MCL samples (Fig. S6D and Table S4).