Effect of iron transferrin on nucleic acid synthesis in phytohemagglutinin-stimulated human lymphocytes

In serum-free cultures of phytohemagglutinin-stimulated human lymphocytes, iron transferrin causes enhanced uptake of both tritiated thymidine and tritiated uridine over that seen with only phytohemagglutinin. This effect is specific for the iron transferrin complex, no enhancement produced by either free iron(III) or apotransferrin. Iron bound to transferrin is quantitatively taken up by stimulated lymphocyte cultures, while under similar conditions only 10% of transferrin-bound zinc is incorporated. The relative specificity of action of iron and zinc on nucleic acid synthesis is discussed.