Immunophenotype of blast cells in acute myelofibrosis

Acute Panmyelosis with Myelofibrosis: Clinical, Immunophenotypic and Cytogenetic Study of Twelve Cases

The clinical, cytogenetic, and immunophenotypic features in 12 adult patients with acute panmyelosis with myelofibrosis (APMF; ICD-0-3: 9931/3; C42.1) are reported (median age: 57 years; f/m = 1.4). The white cell count (WBC) was normal in 3 patients; 9 had leucopenia. The median hemoglobin value was 64.5 g/l, and median platelet count 12 x 10(9)/l. Bone marrow biopsy showed a hypercellular marrow in 10/12 patients with a significant infiltration of pathological blasts (range: 30 - 60%). All the cases had marked reticulin fibrosis. Immunophenotyping of bone marrow blast cells showed the expression of early (CD34) and lineage-unspecified antigens (HLA-DR) in 6/7, and 7/7 patients, respectively. "Early" myeloid antigens (CD13, CD33) were seen in 6/7 and 4/6 patients respectively. Monocyte antigen (CD14) was expressed in 3/7 patients. Megakaryocyte antigen (CD61) and erythroid cell antigen (GpA) were each expressed in only 1 patient. Two patients had expression of CD34, HLA-DR and "early" myeloid antigens by their bone marrow blast cells and 1 of these also had a co-expression of the antigens from a differentiated monocytic cell proliferation (lysozyme+, CD68+). Nonspecific chromosomal aberrations were recorded in 8/10 patients. The median survival was 2 months. These findings suggest an immature myeloid phenotype of blast cells in APMF. In 6/9 patients a leukemic cell differentiation into monocytic, megakaryocytic or erythroid lineage was also demonstrated.

Megakaryocyte markers in myeloproliferative disorders

Identification of megakaryocyte precursors with immunohistochemical methods in bone marrow trephine biopsy specimens (embedded in a plastic resin, Immuno-Bed) was performed from patients with blastic phase of chronic granulocytic leukaemia (five cases), from chronic megakaryocytic-granulocytic myelosis (four cases) and from acute megakaryoblastic leukaemia (11 cases). In megakaryoblasts of bone marrow biopsies immunohistochemical reactions using the ABC method and monoclonal antibodies against von Willebrand antigen and GpIIb/IIIa (CD41) were visible in various percentages depending on the maturation's degree of megakaryocyte precursors. The number of circulating blast cells determined by flow cytophotometry was nearly similar to those of observed in biopsies. The greatest bone marrow reticulin content could be detected in acute megakaryoblastic leukaemia cases. Despite the different clinicopathological entities, the presence of the same phenotype (megakaryoblasts) was associated with a short survival in these haematological malignancies (in CGL MKB phase 4.0, in CMGM MKB phase 4.2, and in AML M7 5.8 months, respectively).