However, immunophenotyping revealed that the acute leukemia was B/M MPAL (in this case, it is also called biphenotypic acute leukemia): in the 14-19-4 BMT series, leukemic blood cells expressed unusual intermediate levels of both lymphoid B220 and myeloid CD11b markers and appeared as CD43+CD19+CD127+ (Fig. 4a), suggesting a blockage of early B-cell development at the pro-B to pre-B stage. This evidence concerns the gene CD19 and acute leukemia.