Removal of transferrin from fetal bovine serum.

An antiserum against purified fetal bovine serum (FBS) transferrin was produced in rabbits. The isolation of anti-bovine transferrin IgG fraction was achieved by ammonium sulfate precipitation of rabbit hyperimmune plasma followed by ion exchange chromatography on diethylaminoethanol (DEAE) cellulose, at both an acidic and basic pH. The various antibody fractions were analyzed by fast protein liquid chromatography (FPLC) on a high-resolution mono-Q column. The specificity and efficiency of the antibody fractions obtained were tested by titration of a constant amount of fetal bovine serum with increasing amounts of antibody. The completeness of removal of the fetal bovine serum transferrin resulting from the formation of the highly stable antibody antigen complex was monitored by immunologic and radioisotope methods. The removal of FBS transferrin by this antibody precipitation technique did not interfere with the ability of added iron 59-tagged human transferrin to deliver iron to rat reticulocytes, as shown in an in vivo incubation model. The method proved to be effective for the fast and complete removal of bovine transferrin from fetal bovine serum in vitro and will be a prerequisite for more detailed studies of the interaction of transferrin of different species with tissue receptors on cell lines in culture without resorting to completely defined culture media.