title: Monoclonal immunoglobulin with antitransferrin activity: A rare cause of hypersideremia with increased transferrin saturation.
abstract: Two unusual but similar cases of very high serum iron, extremely high transferrin concentrations (5.4 to 6.5 g/L), and increased transferrin saturation are reported. No anemia or microcytosis was observed. The ferritin concentration remained within the normal range, and no iron overload was observed. In one case, the in vivo half-life of 59Fe-labeled transferrin was shown to be prolonged (206 minutes versus 75 minutes for controls). In both patients, a monoclonal IgG was observed in the serum. The association between serum transferrin and monoclonal IgG was demonstrated by Western blot analysis and affinity chromatography. We suggest that the transferrin bound to the monoclonal IgG molecule has a prolonged half-life in the circulation, leading to high transferrin concentrations, and that the increased serum iron values prevent the onset of anemia. The antitransferrin activity of monoclonal antibody should be added to the list of situations accounting for elevated serum iron with elevated transferrin saturation.
authors.affiliation: Université Paris 5 René Descartes; Assistance Publique-Hôpitaux de Paris (AP-HP), Laboratoire d'Immunologie, Hôpital Necker, Paris, France.
authors.forename: Marie-Alexandra
authors.initials: MA
authors.lastname: Alyanakian
authors.forename: Youri
authors.initials: Y
authors.lastname: Taes
authors.forename: Mimouna
authors.initials: M
authors.lastname: Bensaïd
authors.forename: Berta
authors.initials: B
authors.lastname: Segovia
authors.forename: Pierre
authors.initials: P
authors.lastname: Aucouturier
authors.forename: Jean-Didier
authors.initials: JD
authors.lastname: Rain
authors.forename: Joris
authors.initials: J
authors.lastname: Delanghe
authors.forename: Bruno
authors.initials: B
authors.lastname: Varet
authors.forename: Carole
authors.initials: C
authors.lastname: Beaumont
mesh_terms: D000911:Antibodies, Monoclonal / Q000097:blood / Q000276:immunology* / Q000302:isolation & purification; D000918:Antibody Specificity; D001853:Bone Marrow / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D005293:Ferritins / Q000097:blood; D005500:Follow-Up Studies; D006207:Half-Life; D006432:Hemochromatosis / Q000175:diagnosis; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology* / Q000302:isolation & purification; D007145:Immunoglobulin kappa-Chains / Q000097:blood / Q000276:immunology* / Q000302:isolation & purification; D007501:Iron / Q000097:blood*; D007504:Iron Radioisotopes / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D010265:Paraproteinemias / Q000097:blood* / Q000276:immunology; D012075:Remission, Spontaneous; D014168:Transferrin / Q000032:analysis / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D007145:Immunoglobulin kappa-Chains; D007504:Iron Radioisotopes; D014168:Transferrin; D005293:Ferritins; D007501:Iron