[Changes in the activity of endonucleolysis of nuclear DNA in children with acute leukemia].

The previously established fact of low activity of Ca, Mg-dependent endonucleolysis of cell nucleus DNA in lymphoproliferative diseases (CME-activity) brought the authors to study intranuclear characteristics of lymphoid cells in childhood acute lymphoblastic leukemia (ALL). The intensity of DNA-endonucleolysis was measured in 0.7% agarose gel using electrophoresis. Peripheral blood and bone marrow samples from 13 untreated ALL patients and 23 children in remission were examined. The age of the patients ranged from 4 to 14 years. CME-activity before treatment appeared to be 2-10 times less than normal in 8 out of 13 patients. In bone marrow cell nuclei CME-activity was universally reduced 3-20-fold. In ALL remission endonuclease activity in blood and bone marrow cells returned to normal.