[Xanthine oxidase activity in mononuclear cells of human blood]

Xanthine oxidase activity has been revealed in human blood mononuclear cells. The enzyme is found in these cells only after solubilization. This may become the explanation for contradiction with other previous data claiming absence of xanthine oxidase in human blood mononuclears. The level of enzyme activity is 2.76 +/- 0.029 mu mol/g protein.min. The latter is readily inhibited with allopurinol and folic acid.