The core set of antibodies used to compound the backbone in the different combinations useful for MRD detection in B-lineage ALL (B-ALL) usually include CD45, CD34, CD19, and CD10 - antigen initially named CALLA (common ALL antigen), expressed with high frequency in childhood BALL.5,13,24,29,36,41,50,54,56 The additional antibodies should be chosen based on the immunophenotype of each case at diagnosis. This evidence concerns the gene CD19 and acute lymphoblastic leukemia.