Cytogenetics and flow cytometry may predict phenotype of CML blast crisis.

Twenty-eight patients with chronic myelocytic leukemia (CML) and the Philadelphia chromosome (Ph1) were monitored using cytofluorometry and cytogenetics. During chronic phase, abnormal populations could be detected using commercially available monoclonal antibodies. These abnormal populations fell into two categories based on the presence or absence of HLA.DR. Patients with HLA.DR+ abnormal cells showed no clonal evolution and progressed to lymphoid blast crisis. Patients with HLA.DR- abnormal cells exhibited chromosomal abnormalities in addition to the Ph1 and progressed to a myeloblastic acute phase.