Interaction of ferritin with serum: implications for ferritin turnover

An interaction between human and rabbit ferritins and serum was demonstrated by a coated tube binding assay, a shift in molecular size on gel filtration and by precipitation of complexes with 3.5% polyethylene glycol 6000. With polyethylene glycol and labelled ferritins, complex formation was inhibited by heating sera to 56 degrees C for 30 min and by addition of EDTA or excess unlabelled ferritins. Human heart ferritin showed the greatest interaction with serum, followed by human spleen ferritin and least of all human plasma ferritin. Ferritins did not appear to bind to IgG or IgM in normal sera. The interaction of 'H' subunit-containing ferritins with serum or plasma may be partly responsible for the rapid clearance of tissue ferritins from the circulation and the absence of acidic isoferritins in the plasma of normal subjects.