title: Lineage identification of acute leukemias: relevance of immunologic and ultrastructural techniques.
abstract: This study assesses the value of immunologic and ultrastructural methods in disclosing the lineage commitment of cells from acute leukemias (ALs). Two hundred and fifty-one ALs were characterized morphologically, cytochemically, and immunologically. Myeloperoxidase (MPO) positivity in > 3% of blasts was regarded as evidence of the myeloid origin of leukemic cells, cytoplasmic CD22 (cCD22) expression was taken as an indication for B-lineage acute lymphoblastic leukemia (ALL), and CD3+ (membrane or cytoplasmic) cases were classified as T-ALL. Diagnosis of minimally differentiated acute myeloid leukemia (AML-M0) was made when blast cells had undifferentiated features by light microscopy, reacted with at least one of the antibodies to myeloid-specific antigens (CD13, CD33, MPO), and lacked CD19, cCD22, and c/mCD3. Megakaryoblastic differentiation was demonstrated by the expression of CD41 and/or CD61. Following these criteria, 209 cases were classified as acute myeloid leukemia (AML) and 39 as ALL. Expression of lymphoid antigens was detected in 45% of AML cases and 30% of ALLs showed myeloid antigens. One case was regarded as a true biphenotypic leukemia because of the combined expression of MPO and CD33 for the myeloid lineage, and cCD3, CD2, and CD5 for the T-cell lineage. Two cases lacked signs of myeloid or lymphoid differentiation and were studied by electron microscopy methods. One displayed platelet peroxidase (PPO) activity and was classified as a megakaryoblastic variant, one other reacted with anti-CD33 and was considered AML-M0. We conclude that light microscopy and standard immunologic methods can accurately demonstrate the lineage orientation in greater than 99% of ALs. Integration with ultrastructural analysis can define the cell nature of virtually all cases of AL.
authors.affiliation: Department of Hematology, University of Rome Tor Vergata, S. Eugenio Hospital, Rome, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Stasi
authors.forename: G
authors.initials: G
authors.lastname: Del Poeta
authors.forename: A
authors.initials: A
authors.lastname: Venditti
authors.forename: A
authors.initials: A
authors.lastname: Bruno
authors.forename: G
authors.initials: G
authors.lastname: Suppo
authors.forename: G
authors.initials: G
authors.lastname: Aronica
authors.forename: G
authors.initials: G
authors.lastname: Di Carlo
authors.forename: G
authors.initials: G
authors.lastname: Papa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001853:Bone Marrow / Q000648:ultrastructure*; D002454:Cell Differentiation; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D007938:Leukemia / Q000145:classification* / Q000276:immunology / Q000473:pathology; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged