title: Anti-c-Mpl (thrombopoietin receptor) autoantibody-induced amegakaryocytic thrombocytopenia in a patient with systemic sclerosis.
abstract: Amegakaryocytic thrombocytopenia (AMT) associated with systemic sclerosis (SSc) has been described in several case reports, but the underlying mechanisms have not been identified. Here we describe a rare case of SSc accompanied by thrombocytopenia and megakaryocytic hypoplasia, in which autoantibody against thrombopoietin receptor (c-Mpl) was detected. A 61-year-old woman with limited SSc was admitted to our hospital because of severe thrombocytopenia (platelet count 0.2 x 10(4)/mm(3)) with gingival bleeding. Her bone marrow was hypocellular with absent megakaryocytes, consistent with AMT. Treatment with corticosteroids and intravenous immunoglobulin infusions resulted in an increased platelet count, and she sustained a remission over a 1-year period, with a platelet count averaging 10.0 x 10(4)/mm(3). Her serum was strongly positive for anti-c-Mpl antibody, and IgG fraction purified from her serum inhibited thrombopoietin-dependent cell proliferation in vitro. Our case report suggests that AMT in patients with SSc could be mediated by the anti-c-Mpl antibody, which functionally blocks an interaction between thrombopoietin and c-Mpl.
authors.affiliation: Department of Internal Medicine, Kawasaki Municipal Hospital, Kanagawa, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Katsumata
authors.forename: Takahiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Masataka
authors.initials: M
authors.lastname: Kuwana
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hattori
authors.forename: Satoshi
authors.initials: S
authors.lastname: Akizuki
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sugiura
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Matsuoka
mesh_terms: D001323:Autoantibodies / Q000276:immunology*; D001854:Bone Marrow Cells / Q000473:pathology; D005260:Female; D005938:Glucocorticoids / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D016756:Immunoglobulins, Intravenous; D007275:Injections, Intravenous; D008533:Megakaryocytes / Q000473:pathology*; D008775:Methylprednisolone / Q000008:administration & dosage / Q000627:therapeutic use; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000276:immunology*; D011518:Proto-Oncogene Proteins / Q000276:immunology*; D020551:Pulse Therapy, Drug; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000150:complications / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology*; D018121:Receptors, Cytokine / Q000276:immunology*; D053628:Receptors, Thrombopoietin; D012074:Remission Induction; D012595:Scleroderma, Systemic / Q000150:complications / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology*
chemical_list: D001323:Autoantibodies; D005938:Glucocorticoids; D016756:Immunoglobulins, Intravenous; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D018121:Receptors, Cytokine; D053628:Receptors, Thrombopoietin; C082218:MPL protein, human; D008775:Methylprednisolone