The role of transferrin in lymphocyte transformation.

The ability of mouse lymphocytes to transform in a serum-free medium in response to Concanavalin A was found to depend upon the presence of transferrin. Iron chelates were ineffective, as also were monoferric transferrin fragments, but both homologous and heterologous transferrins promoted transformation. Optimal transformation occurred with 10-50 micrograms/ml of transferrin, and at 30-70 per cent iron saturation. Transferrin was bound by the transforming cells, and subsequently released without degradation following the delivery of iron. Iron uptake preceded DNA synthesis. Iron chelates, despite their inability to promote transformation, could also deliver iron to lymphocytes. It is postulated that transferrin may fulfil functions additional to that of supplying iron.