Determination of DNA topoisomerase II in newly diagnosed childhood acute lymphoblastic leukemia by immunocytochemistry and RT-PCR.

The expression of DNA-topoisomerase II was analysed at the protein level in newly diagnosed cases of acute lymphoblastic leukemia (ALL) in children. Blast cells obtained from 81 children with untreated ALL were determined by means of immunocytochemistry. Of the ALL, 49 (60%) were positive for topoisomerase II and 32 (40%) negative. No significant correlation was found between the expression of topoisomerase II and the relapse rate or relapse-free intervals. These results were substantiated by determining the topoisomerase II mRNA expression in a collective of 21 patients by semiquantitative PCR. The PCR-assay and immunocytochemistry corresponded in 13 of 21 cases (62%).