Abstract: BACKGROUND ＆ AIM: We made anti-human diamine oxidase (DAO) monoclonal antibody, analyzed the expression of diamine oxidase in colorectal tissue to assess its significance in pathologic diagnosis and its correlation with clinicopathologic parameters. MATERIALS AND METHODS: We used immunohistochemical technique to study the expressions of DAO in different colorectal tissues.The expression was compared with clinicopathological features of colorectal neoplasia. RESULTS: DAO positive expression was found in cell cytoplasm. There were significant differences among the colorectal carcinomas, tous adenomatous polyps and mucosa adjacent to cancer. DAO positive expression rate in villous adenoma was significantly higher than that of tubulo adenoma(P<0.05). DAO was expressed in dysplatic tissues, and frequency increased with the progression of the dysplasia. CONCLUSION: DAO may be associated with the growth of colorectal neoplasia. It could be an early biomarker in human colorectal carcinomas and could predict growth of tumor at an early stage.

Key words: diamine oxidase, colorectal neoplasia, immunhistochemistry