ABSTRACT
Objective To study the mechanism of oxidative stress involved in the pathogenesis and relapse of acute monocytic leukemia (M5 ).Methods We detected reactive oxide species (ROS)levels,conducted plasma analysis obtained from 76 M5 patients at diagnosis and at relapse,and observed the ultrastructure of mitochondria of mononuclear cells in peripheral blood by transmission electron microscope.Results Compared with that in the control group,the average fluorescence intensity of intracellular ROS was significantly increased in M5 groups, especially in the relapse patients (P < 0.05 ).Low total antioxidative capacity (T-AOC)and antioxidant enzyme activity were characteristic of M5 at both diagnosis and relapse. However, lactate dehydrogenase (LDH ), malondialdehyde (MDA)and 8-hydroxy-2’-deoxyguanine (8-OHdG)increased significantly at both diagnosis and relapse (P < 0.05 ).Prominent ultrastructural abnormalities (mitochondrial swelling,outer membrane blebs,and aberrant cristae disorder)were present in patients with primary M5,and they were obviously abnormal in relapsing M5 patients.Conclusion Oxidative stress is the initiating factor of M5.Mitochondria are the main intracellular location for ROS generation.To maintain the dynamic balance between ROS and antioxidant defence may be the critical factor for preventing relapse.