Immunophenotype of Abnormal Metaphases Demonstrating Multilineage Involvement in Myelodysplastic Syndromes

Eight patients with myelodysplastic syndrome (MDS) and chromosome abnormalities were studied by a combined method which allows simultaneous analysis of the karyotype and immunophenotype of the same mitotic cell. To determine the cell lineages with abnormal karyotype, monoclonal antibodies in the alkaline phosphatase-antialkaline phosphatase (APAAP) staining methods were used All patients with MDS showed metaphases with abnormal karyotype in cells belonging to granulocytic/monocytic lineage. In 7 patients studied the leukaemic process also involved erythrocytic and/or megakaryocytic lineages. In 4 patients with 5q- chromosome it was evident that at least the granulocytic/monocytic and erythrocytic cell lineages participated in the clonal proliferation. One patient with 5q- chromosome at initial diagnosis showed a shift from megakaryocytic to a granulocytic/monocytic cell population at the time of acute leukaemia These findings indicate multi-lineage involvement in patients with MDS who have karyo-typic abnormalities.