The proportion of abnormal karyotypes in acute leukemia samples related to method of preparation

Bone marrow and peripheral blood were studied from 200 patients with acute leukemia [109 with acute myeloid leukemia (AML), 91 with acute lymphoblastic leukemia (ALL)] who had samples cultured for varying times and who had a mixture of chromosomally abnormal and normal cells. The mean percentage of abnormal metaphase cells increased with culture time. The peak was reached at 48 hours and declined slightly after 72 hours in culture for ALL patients. The mean percentage of abnormal cells increased up to 72 hours in culture for AML patients. In 68 patients (31 AML and 37 ALL), cytogenetic data were available from samples processed with both direct preparations and culture methods. The percentage of abnormal cells increased after culture in 49 patients (23 AML and 26 ALL), while it decreased or remained at the same level in 19 patients. For AML patients, the mean percentage of abnormal cells was significantly different between direct (38%) and cultured preparations (63%), (p less than 0.001). Seven of 9 patients with AML who showed a greater than 50% increase in abnormal cells after culture had either a t(8;21), t(15;17), or abnormalities involving 11q23. The two patients who showed a significant decrease in abnormal cells both had a translocation involving 11q13. Compared with ALL, more AML patients showed greater than 80% abnormal bone marrow metaphase cells at diagnosis or at relapse.