Host-associated iron transfer factor in normal humans and patients with transfusion siderosis.

A low molecular weight iron-binding substance that promotes bacterial growth in vitro by increasing iron availability was identified in human blood and urine. Partial purification and physical characterization indicate that this factor is similar to the host-associated iron transfer factor (HAITF) previously isolated from mammalian tissue. HAITF was found to be significantly elevated in the blood of patients with thalassemia who have transfusional siderosis. The level of HAITF in the blood of these patients was also found to correlate with that of serum iron and serum glutamic-oxaloacetic transaminase (SGOT) but not with that of serum ferritin. Thus, elevated blood levels of HAITF may explain the increased susceptibility to infection seen in patients with iron overload. Its physiologic role, however, may involve the transport of iron within cells.