title: The neonatal Fc receptor (FcRn) is not required for IVIg or anti-CD44 monoclonal antibody-mediated amelioration of murine immune thrombocytopenia.
abstract: To definitively determine whether the neonatal Fc receptor (FcRn) is required for the acute amelioration of immune thrombocytopenia (ITP) by IVIg, we used FcRn-deficient mice in a murine ITP model. Mice injected with antiplatelet antibody in the presence or absence of IVIg displayed no difference in platelet-associated IgG between FcRn deficient versus C57BL/6 mice. FcRn-deficient mice treated with high-dose (2 g/kg) IVIg or a low-dose (2 mg/kg) of an IVIg-mimetic CD44 antibody were, however, protected from thrombocytopenia to an equivalent extent as wild-type mice. To verify and substantiate the results found with FcRn-deficient mice, we used β(2)-microglobulin-deficient mice (which do not express functional FcRn) and found that IVIg or CD44 antibody also protected them from thrombocytopenia. These data suggest that for both high-dose IVIg as well as low-dose CD44 antibody treatment in an acute ITP model, FcRn expression is neither necessary nor required.
authors: Canadian Blood Services, Keenan Research Centre in the Li Ka Shing Knowledge Institute of St Michael’s Hospital, University of Toronto, Toronto, ON, Canada.
authors: Andrew R
authors: AR
authors: Crow
authors: Sara J
authors: SJ
authors: Suppa
authors: Xi
authors: X
authors: Chen
authors: Patrick J
authors: PJ
authors: Mott
authors: Alan H
authors: AH
authors: Lazarus
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D001323:Autoantibodies / Q000627:therapeutic use*; D004195:Disease Models, Animal; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000502:physiology*; D006801:Humans; D018960:Hyaluronan Receptors / Q000737:chemistry*; D016756:Immunoglobulins, Intravenous / Q000627:therapeutic use*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D010976:Platelet Count; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000097:blood / Q000276:immunology / Q000517:prevention & control*; D011961:Receptors, Fc / Q000235:genetics / Q000502:physiology*; D001613:beta 2-Microglobulin / Q000235:genetics / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; D001323:Autoantibodies; C476399:Cd44 protein, mouse; D015395:Histocompatibility Antigens Class I; D018960:Hyaluronan Receptors; D016756:Immunoglobulins, Intravenous; D011961:Receptors, Fc; D001613:beta 2-Microglobulin; C100688:Fc receptor, neonatal