[Hybrid leukemia among acute childhood leukemias]

Four children with the acute leukemia are presented. Their blasts shown the presence of 2 cellular lines markers. Coexistence of markers in the blasts was detected with the technique of double staining the blasts from the bone marrow with: alkaline phosphatase-anti-alkaline phosphatase, and peroxidase with the use of monoclonal antibodies series. Analysis of blasts phenotype with monoclonal antibodies confirm the occurrence of leukemias different from the normally programmed cellular line. Deviations of leukemic cells phenotype may be explained with the fact that leukemogenesis is not an absolute block of cells differentiation but combines maturation disorders and proliferation enabling expression normally absent antigens. It confirms the concept of line preservation and presentation of "earlier frozen" phenotype, and explains the occurrence of leukemias in which blasts present phenotype of one line which does not comply with cell differentiation pattern. Further genotypic studies are necessary to clarify pathogenesis and origin of such blasts. Consequently examination of the larger group of patients with hybrid leukemias will enable conclusions concerning prognostic value of such findings and necessity of introduction of the special therapies.