IMMUNOHISTOCHEMICAL LOCALIZATION OF XANTHINE-OXIDASE IN HUMAN TISSUES

We evaluated the immunohistochemical localization of xanthine oxidase in various human tissues. Xanthine oxidase was purified from cadaver l iver. Polyclonal antibody against xanthine oxidase was raised in a rab bit. Immunoblot analysis showed that the raised antibody reacted speci fically with one band whose position corresponded with that of the pur ified enzyme. Immunostaining of paraffin-embedded tissue sections show ed intense reactivity in the following tissues: surface epithelium of tongue, esophagus, and trachea, sweat glands, and mammary glands. Weak , but positive, reactivity was observed in other tissues, such as glan dular cells of the small and large intestine and renal tubules, skelet al muscle, gastric epithelial cells, alveoli of the lung, spleen, and liver cytoplasm. Xanthine oxidase staining was observed in infiltratin g lymphocytes (probably T-lymphocytes but not in B-lymphocytes) in inf lammatory lesions of the small and large intestine. Its ubiquitous loc alization suggests that xanthine oxidase is involved in cell prolifera tion/differentiation, the defense mechanisms, and in the pathogenesis of reperfusion tissue injury.