Highly sensitive and reliable chemiluminescence method for the assay of superoxide dismutase in human erythrocytes

Superoxide dismutase in human erythrocytes was assayed by the inhibition of highly diluted erythrocyte lysates on 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazol[1,2-alpha]pyra zin-3-one- dependent luminescence induced by the hypoxanthine-xanthine oxidase system. Our chemiluminescence procedure gave 95-times higher sensitivity than the cytochrome c method. The concentration of superoxide dismutase in erythrocytes of Down's syndrome patients was approx. 1.8-times higher than that of normal humans.