Quantitative analysis of chromosomal G-bands in human hematopoietic disorders by methotrexate synchronization technique.

Chromosomal G-bands in an improved morphology were demonstrated in bone marrow and unstimulated blood cultures from 12 patients with hematopoietic disorders and 1 with another disease. The procedure used was a cell synchronization technique involving methotrexate or cytosine-arabinoside and thymidine release. Quantitative analyses were made comparatively between synchronized and nonsynchronized (control) cultures in each patient. Mitotic indices varied with the individual. The average number of G-bands per haploid set increased statistically in 8 cases, and the count was often over 400. Improved chromosomal banding patterns in the synchronized preparation resulted in easy and precise identification of chromosome rearrangements in three patients with chronic myeloid leukemia (CML), two with acute myeloblastic leukemia (AML), and three with anemias. Normal cells were more frequently observed in synchronized overnight cultures than in control cultures from two patients with an admixture of normal and abnormal metaphases. There was a slight increase in a minor abnormal clone in the synchronized cultures from one patient. These findings indicate that the cell synchronization technique we use is not only useful in improving chromosome morphology, but is also efficient in detecting both normal and abnormal metaphases.