PRODUCTION OF SUPEROXIDE ANION BY POLYMORPHONUCLEAR LEUKOCYTES FROM DIABETIC-PATIENTS WITH OR WITHOUT DIABETIC-RETINOPATHY

Oxygen free radicals have been implicated in the pathogenesis of diabe tic microangiopathy. The production of superoxide anion (O2(-.)) by po lymorphonuclear leukocytes (PMNs) from 45 insulin-dependent diabetes m ellitus patients in the resting state and in response to a soluble sti mulus (phorbol myristate acetate) was measured spectrophotometrically and compared with that of 15 age and sex matched controls. The resting superoxide anion production by PMNs from diabetic patients was signif icantly higher than that of controls (2.17 +/- 1.32 and 1.35 +/- 0.6 n mol/10(5) cells/60 min respectively; p = 0.037). In contrast, PMNs fro m diabetic patients released significantly lower levels of superoxide anion compared to controls in response to phorbol myristate acetate st imulation (2.33 +/- 2.04 and 3.55 +/- 0.98 nmol/10(5) cells/60 min res pectively; p = 0.044). The stimulated superoxide anion production was significantly higher in diabetic patients with retinopathy compared to diabetic patients without retinopathy (2.71 +/- 2.08 and 1.3 +/- 1.6 nmol/10(5) cells/60 min respectively; p = 0.02). Furthermore, stimulat ed PMNs from diabetic patients with proliferative retinopathy generate d superoxide anion at significantly higher rates than did those from d iabetics with nonproliferative retinopathy or without retinopathy (3.8 +/- 1.5, 2.08 +/- 2.1 and 1.3 +/- 1.6 nmol/10(5) cells/60 min respect ively; p = 0.005). These results suggest that reactive oxygen species produced by PMNs may play a role in the progression of diabetic retino pathy.