title: Cell surface phenotyping of megakaryoblasts.
abstract: Surface phenotypic characterization of megakaryoblasts, identified by platelet peroxidase activity, was investigated in four patients who showed increased proliferation of megakaryoblasts: one patient with typical features of acute leukemia, one presenting with acute myelofibrosis, and two with Down's syndrome in whom blasts disappeared spontaneously (transient abnormal myelopoiesis, TAM). MY10 and/or MY9 antigens were expressed on the surface of some megakaryoblasts, but MY7, and MY4, antigens specific to granulocytic or monocytic cells, were not. Some megakaryoblasts were positive for only anti-HLA-DR antibodies. It was speculated that, during the differentiation of the megakaryocytic lineage, MY9 antigen appears transiently on the surface of megakaryoblasts that have lost HLA-DR antigens and have gained the glycoprotein IIb/IIIa antigen. This study also demonstrated that the proliferating blasts in some patients with TAM were mainly megakaryoblasts and suggested that the target cells in TAM are CFU-GEMM.
mesh_terms: D000293:Adolescent; D000951:Antigens, Neoplasm / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis*; D002454:Cell Differentiation; D004314:Down Syndrome / Q000473:pathology; D006684:HLA-DR Antigens / Q000032:analysis; D006412:Hematopoietic Stem Cells / Q000032:analysis / Q000145:classification*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007527:Isoenzymes / Q000032:analysis; D007947:Leukemia, Megakaryoblastic, Acute / Q000473:pathology*; D008533:Megakaryocytes / Q000032:analysis*; D009363:Neoplasm Proteins / Q000032:analysis; D009195:Peroxidase; D010544:Peroxidases / Q000032:analysis; D010641:Phenotype; D010980:Platelet Membrane Glycoproteins / Q000032:analysis; D055728:Primary Myelofibrosis / Q000473:pathology
chemical_list: D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D006684:HLA-DR Antigens; D007527:Isoenzymes; D009363:Neoplasm Proteins; D010980:Platelet Membrane Glycoproteins; D010544:Peroxidases; D009195:Peroxidase