ABSTRACT
Human serum amine oxidase (HSAO) and diamine oxidase (DAO) are commonly considered the copper-dependent amine oxidases in the human body. DAO activity in humans has been found either in serum, and in normal and pathological tissues and fluids; it was purified from placenta, intestinal mucosa, plasma during pregnancy or after heparin administration, and amniotic fluid. Several methods have been proposed for HSAO assay employing different substrates, but the majority of studies concerning HSAO in different clinical conditions were carried out with benzylamine as substrate. The clinical employment of HSAO assays appears to be restricted to the evaluation of liver fibrosis, and, possibly, to the detection of neoplasms. The physiological role of DAO is related to the biological function of its natural substrates, namely histamine and polyamines. In humans, DAO has been detected in intestinal mucosa, kidney, spleen and liver, placenta, eosinophil and neutrophil granulocytes, semen, lymph, plasma, amniotic fluid, and urine.
