Superoxide dismutase activity in lymphocytes and polymorphonuclear cells of diabetic patients

Copper-zinc superoxide dismutase (Cu,Zn-superoxide dismutase) activity was evaluated in lymphocytes and polymorphonuclear cells of insulin-dependent (n = 33) and non-insulin-dependent (n = 34) diabetic patients. A commercial method for the measurement of superoxide dismutase activity was adapted for use on a discrete analyser and evaluated for interference by other antioxidants with superoxide anion-scavenging properties. In comparison to healthy control subjects (n = 32), a significantly lower Cu,Zn-superoxide dismutase activity was found in both lymphocytes and polymorphonuclear cells of insulin-dependent (2.08 +/- 0.58 vs. 1.70 +/- 0.46 U/mg protein, p < 0.05, and 1.06 +/- 0.46 vs. 0.64 +/- 0.40 U/mg protein, p < 0.001, respectively) and non-insulin-dependent diabetic patients (2.08 +/- 0.58 vs. 1.61 +/- 0.48 U/mg protein, p < 0.01, and 1.06 +/- 0.46 vs. 0.53 +/- 0.24 U/mg protein, p < 0.001, respectively). There was a week, but significant negative correlation between age and Cu,Zn-superoxide dismutase activity in lymphocytes and polymorphonuclear cells (r = -0.22 and r = -0.28, p < 0.05, respectively), whereas no influence of gender, diabetes duration and glycaemic control was observed. The results indicate that diabetes mellitus could elicit a significant disturbance in superoxide anion-scavenging potential of lymphocytes and polymorphonuclear cells.