Superoxide dismutase in red blood cells: method of assay and enzyme content in normal subjects and in patients with beta-thalassemia (major and intermedia).

The applicability to red blood cells of two widely used methods for spectrophotometric assay of superoxide dismutase activity has been tested, in view of the demand for routine screening of the level of this enzyme in various circumstances of hematological interest. The nitro blue tetrazolium reduction method was found to be inapplicable, even after removal of hemoglobin by chloroform-ethanol extraction. On the other hand, the epinephrine oxidation method gave reliable values after chloroform-ethanol extraction. The enzyme content in normal adults was found to be 6.2 +/- 1.4 X 10(15) gr. per red blood cell. No significant change in the enzyme content was found in 19 patients with beta-thalassemia major and 5 patients with beta-thalassemia intermedia, indicating no influence on the level of this enzyme by the increased flux of oxygen radicals which is to be expected in thalassemic red blood cells.