BIOMED-1 Concerted Action report: Flow cytometric characterization of CD7+ cell subsets in normal bone marrow as a basis for the diagnosis and follow-up of T cell acute lymphoblastic leukemia (T-ALL)

Immunophenotyping of acute leukemias and myelodysplastic syndromes

“…In fact, during the last decade it has been shown (23,24,42,(45)(46)(47) that both precursor-B and T ALL display aberrant phenotypes in more than 95% of the cases. This allows for an unequivocal discrimination between normal and leukemic lymphoid precursors in the BM (45)(46)(47), peripheral blood (PB) (45), and other body fluids (23,48). The occurence of these aberrant phenotypes can only be explained because of the existence of underlying genetic abnormalities in leukemic blast cells.…”

“…However, when individually considered, none of these markers is specific to myeloid leukemic cells (46,47,59,60), and their combined expression is also found in the more immature, uncommitted CD34ϩ hematopoietic precursors (38,61). At present, cytoplasmic expression of myeloperoxidase (MPO), lisozyme, and tryptase (with the B12 clone) are considered as the most characteristic markers of myeloid cells (40,62,63).…”

“…Biphenotypic and bilineal acute leukemias should be specifically identified as different from both ALL with expression of myeloid associated markers and AML showing reactivity for lymphoidrelated antigens. These latter cases may represent more than 20% of all AL (40,46,47,59). In addition, they should also be separately considered from ALL patients with precursor-B/T phenotypes and from AML cases in which blast cells display phenotypic features characteristic of more than one cell lineage.…”

“…For that purpose, it is required that leukemic cells display aberrant phenotypes, since with a few exceptions, the detection of tumor specific antigens cannot be applied routinely (23,24). Aberrant phenotypes are present in most ALL (Ͼ95%) (23,24,(45)(46)(47)85) and AML cases (Ͼ75%) (23,24,(71)(72)(73)(74)(75)(76). They are typically defined by: 1) cross-lineage antigen expression (e.g., expression of CD5 in AML or CD33 in ALL); 2) asynchronous antigen expres- D, and F).…”

Analysis of minimal residual disease in childhood acute lymphoblastic leukemia: comparison between RQ-PCR analysis of Ig/TcR gene rearrangements and multicolor flow cytometric immunophenotyping

“…All antibody combinations used for followup were chosen based on aberrant marker expression, by comparison to the normal bone marrow patterns determined during BIOMED-1 Concerted Action 'Investigation of Minimal Residual Disease in Acute Leukemia: International Standardization and Clinical Evaluation'. 31,32 Cells (10 5 -1.5 Â 10 6 ) were analyzed using a 'live gate' acquisition method, giving sensitivity for MRD detection of at least 10 À4 .…”