Decreased oxidant-induced proteolysis in erythrocytes with enhanced antioxidative defence enzymes due to Down's syndrome.

Erythrocytes of Down syndrome patients, having increased activity of superoxide dismutase and glutathione peroxidase, showed a similar increase in intracellular proteolysis upon stimulation with 1 mmol/l phenylhydrazine than normal erythrocytes. There were no differences in the magnitude of Heinz body formation following the treatment or in the proteolysis of exogenous oxidized substrate. These results demonstrate a protective role for endogenous antioxidative enzymes in the protein damage by oxidative stress which triggers intracellular proteolysis.