Multiple lineage reactivity in childhood leukemia

Immunophenotypic analysis of acute lymphocytic leukemia

Acute lymphoblastic leukemia (ALL) is one of the most common hematologic malignancies. Flow cytometry is an integral part of ALL diagnosis and also provides significant patient prognostic information. This article is a practical review of the basic principles of the flow cytometric evaluation of acute leukemias, the interpretation of flow cytometric data, and the management of practical problems such as aberrant antigen, hematogones, bone marrow regeneration, and minimal residual disease.

Multiphenotypic acute leukemias: clinicopathologic correlations and response to therapy

Multiphenotypic acute leukemias (MAL), defined by the coexpression on most blast cells of antigens classically attributed to different lineages, remain a rare event. We isolated a series of 26 such cases from a cohort of 1565 leukemic patients whose cells were immunophenotyped at diagnosis. Markers of B and myeloid lineage (BM) were associated in 16 cases (62%), 3 coexpressed B and T markers (BT), and T-cell and myeloid antigens (TM) were found in 7 (27%). A tumoral syndrome was observed in 69% of the patients, without significant differences between the immunophenotypic subgroups. Median event free survivals in the three immunophenotypic subgroups as defined were respectively 24 months for BM-MAL, 4 months for TM-MAL and 7 months for BT-MAL respectively. The poorer prognosis of TM-MAL was significantly different from that of BM-MAL (p < 0.001). This concurred with the poorer prognosis associated with CD7 expression or absence or CD10, both characteristic features of TM-MAL.

Down's syndrome and mixed acute leukemia in infants

The routine use of panels of monoclonal antibodies has been complementary to the French-American-British (FAB) leukemia classification, and has unmasked the occurrence of mixed acute leukemia (myeloid-lymphoid). It is widely accepted that children with Down's syndrome (DS) have a high incidence of acute leukemia. There is an extensive body of literature emphasizing the cytogenetic findings in these children. However, information as to the immunophenotype is often limited to the lymphoid surface determinants. The authors report two children with DS whose leukemic blasts were studied with a panel of 17 monoclonal antibodies (myeloid, lymphoid, and megakaryocytic) by flow cytometric examination and were classified as biphenotypic acute leukemia. The blast population coexpressed myeloid and T-cell surface markers. The lymphoid origin was ruled out on the basis of negative terminal deoxynucleotidyl transferase and molecular analysis demonstrating germline configuration for the JH and beta TCR genes.