Characterization of leukemic cells in CD2/CD19 double positive acute lymphoblastic leukemia

Acute lymphoblastic leukemia with coexpression of CD56 and CD57: case report

The authors present the clinical profile of a 6-year-old girl with an unusual immunophenotype of acute lymphoblastic leukemia (ALL). At the initial presentation, massive hepatosplenomegaly developed. The leukemic cells were myeloperoxidase-negative and morphologically lymphoblastic. These cells were positive for B-precursor-cell (CD10, CD19) antigens and natural killer cells (CD56, CD57). Rearrangements of both immunoglobulin heavy chain alleles and monoallelic rearrangement of T-cell receptors (TCRs)-beta and -delta genes, but not that of TCR-gamma gene, were detected, suggesting that these cells being of B-precursor origin. The patient received chemotherapy for extremely high-risk ALL with a good response. To the authors' knowledge, this is the first pediatric case describing coexpression of CD56 and CD57 on B-lineage ALL.

Flow cytometric analysis of cell-surface and intracellular antigens in the diagnosis of acute leukemia

To evaluate the usefulness of flow cytometric detection of intracellular antigens (Ags) in establishing proper lineage affiliation and its contribution to the diagnosis of acute leukemia, we studied 100 consecutive patients in whom acute leukemia was diagnosed between January 1997 and July 1998. Immunological classification was assessed using a three-line panel of monoclonal antibodies for phenotypic characterization of leukemic blast cells as proposed at the First Latin American Consensus Conference for Flow Cytometric Immunophenotyping of Leukemia. We found 74 cases of B-cell lineage acute lymphoblastic leukemia (ALL), seven cases of T-cell ALL, and 19 cases of acute myeloid leukemia (AML). In this study cytoplasmic (cy) CD79a, cyCD22, cyCD3, and cyMPO were highly sensitive, specific B, T, and myeloid markers that were expressed in virtually all cases of B and T cell ALL and in all subtypes of AML. Applied in combination with immunophenotyping this knowledge led to improvement in diagnostic precision and refinement of immunological classification, ensuring the selection of the most appropriate therapy for the patients studied. In conclusion, intracellular Ags detection was of utmost importance in establishing correct lineage affiliation in cases lacking expression of B, T, or myeloid surface Ags or disclosing equivocal or ambiguous immunophenotypic features and in identifying biphenotypic acute leukemia. In combination with FAB morphology and immunophenotyping, we were able to reliably classify all patients with acute leukemia in this study.