Abstract
Catalase (CAT), glutathione peroxidase (PGx), as well as superoxide dismutase (SOD), which are known to protect membrane from oxidative damage, were examined in 24 patients with myeloproliferative disorders, including twelve patients with chronic myelogenous leukemia (CML), six with essential thrombocythemia (ET) and six with polycythemia vera (PV). The CAT activities were significantly decreased in the platelets of ET and PV as compared with normal subjects, however it was normal in those of CML. The GPx was also decreased in some patients with these disorders, whereas SOD was increased in some patients. The individual data were further evaluated about the interrelationship among these three enzymes. Two of ET (2/6) and one of PV (1/6) didn't show increased SOD activities as to compensate the reduced CAT or GPx and two of them had the symptom of bleeding tendency and decreased platelet aggregability. The rest of the patients exhibited compensatory high SOD activities for the other decreased enzymes and each patient had never experienced bleeding tendency. These findings suggest that the balance of these three enzyme activities might be playing an important role in the hemostatic function of platelet in these thrombocythemic states.
