Cytogenetic analysis of leukaemic colonies from acute and chronic myelogenous leukaemia

We have utilized the blast cell assay of Buick et al. (1977) to grow and subsequently cytogenetically analyze cultured colony forming cells (CFUs) from patients with acute and chronic myelogenous leukaemia (AML, CML). Cytogenetic analysis of CFUs was successful in 30/36 cases (83%), a success rate similar to direct harvesting techniques. Identical clonal chromosomal abnormalities demonstrated by direct techniques were also observed in CFUs from AML and CML. Removal of T-precursor cells by E-rosetting prior to plating did not eliminate growth of karyotypically normal cells. The combination of morphologic and cytogenetic studies performed clearly established that the assay system supports the growth of leukaemic progenitors. Although both karyotypically normal and abnormal leukaemic colonies grew in this assay, growth of leukaemic colonies was much more likely if the plated cells were karyotypically abnormal (P = 0.010). Leukaemic colony growth was also more frequent if the tritiated thymidine labelling index (LI%) of plated cells was greater than or equal to 5% (P = 0.018). Leukaemic colonies were most likely (P = 0.018) to have been derived from plated cells with both abnormal karyotype and high LI% (greater than or equal to 5%). Cytogenetic analyses from cultured cells revealed only those karyotypic features found in the uncultured cells (i.e., no additional abnormal sublines were found). However, in most cases, the greatly enhanced number and quality of mitotic figures allowed for more detailed banding analysis.