Chronic myelocytic leukaemia: cytogenetical studies on haemopoietic colonies and diffusion chamber cultures.

In 20 patients with chronic myelocytic leukaemia in the chronic phase or in blast crisis, several in vitro (CFU-C, BFU-E) and in vivo (diffusion chamber) culture techniques were used to demonstrate the existence of a still diploid cell clone. In 4 out of 12 patients in the chronic phase, Ph1-negative metaphases were found in the various cultures for haemopoietic progenitor cells but not in the standard suspension cultures used for cytogenetics. However, all the 8 patients investigated during blast crisis had only Ph1-positive and other abnormal clones, indicating the loss of the diploid clone during progression of the disease.