Diamine oxidase is important in assessment of polyamine effects on hemopoietic cell proliferation in vitro.

A difference was observed in the effect of difluoromethlyornithine (DFMO), a specific inhibitor of ornithine decarboxylase, on human and murine granulocyte-macrophage precursor cell (CFU-C) proliferation in vitro, in the presence of fetal bovine serum (FBS) and horse serum (HS). A dose of DFMO which almost totally abolished CFU-C colonies in cultures containing FBS had no effect or very little effect on CFU-C in cultures supplemented with HS. This effect could be reversed by aminoguanidine reacting with diamine oxidase (DAO), which is present in FBS but not in HS. The importance of DAO in the assessment of polyamine effects is also suggested by decreased colony formation in cultures containing HS and DFMO only after the addition of this enzyme. Additionally, Mo T cell line cultures containing DFMO demonstrated a substantially lower intracellular concentration of putrescine in the presence of FBS rather than HS.