Inhibition of erythroid and granulocyte-macrophage colony formation by non-transferrin-bound iron in vitro: protective effect of apotransferrin.

Objectives: The aim of the study was to investigate in vitro the effect of free iron on erythroid and granulocyte-macrophage colony formation and the effect of binding free iron with apotransferrin.

Methods: Normal haematopoietic progenitors were cultured in vitro with different concentrations of free iron in the form of ferric nitrilotriacetic acid (FeNTA). Parallel cultures were performed after the preincubation of FeNTA with apotransferrin.

Results: Free iron inhibited colony formation by erythroid and granulocyte-macrophage progenitors and reduced the size of the colonies in a dose-dependent manner. Preincubation of FeNTA with apotransferrin diminished the inhibitory effect of FeNTA on colony formation increasing both the number and the size of colonies.

Conclusions: Free iron was toxic to haematopoietic progenitors in in vitro cultures; the toxic effect could be reduced with apotransferrin.