Fluorescence in situ hybridization studies of interphase nuclei for assessing response to therapy in patients with chronic myeloid leukemia.

We used two-color fluorescence in situ hybridization (FISH) to detect BCR/ABL fusion in interphase nuclei in bone marrow of 17 patients with chronic myeloid leukemia (CML) before and in the course of interferon therapy. The results of FISH were compared with the data of conventional cytogenetic investigation (G- or Q-banding) of the same specimens. Changes in percentage of Ph-positive nuclei correlated with variations in percentage of Ph-positive metaphases. An overall difference in the classification of patients by conventional cytogenetics and FISH based on the percentage of Ph-positive cells was not observed. This FISH method is reproducible, relatively easy to perform, and reliable for monitoring patients with CML.