Transferrin induces maturation of neutrophil granulocyte precursors in vitro

Previous studies showed that dialyzed serum from guinea pigs contained a factor which induces guinea pig granulocyte precursors to form mature neutrophil granulocytes in vitro. We show here that this maturation inducing activity of serum is associated primarily with transferrin. This activity is not species specific since both guinea pig and human transferrin serve equally well in this capacity. These findings raise the possibility that transferrin could serve as a physiological regulator of granulocyte maturation.