CD19 is a B-lymphocyte surface antigen which is expressed in over 95% of B-cell malignancies including B-cell non-Hodgkin lymphoma (B-NHL), B-cell acute lymphoblastic leukemia (B-ALL), and chronic lymphocytic leukemia (CLL) [11,12]. This evidence concerns the gene CD19 and precursor B-cell acute lymphoblastic leukemia.