title: Two cases of refractory thrombotic thrombocytopenic purpura associated with collagen vascular disease were significantly improved by rituximab treatment.
abstract: Thrombotic thrombocytopenic purpura (TTP) is a rare disorder of small vessels. TTP is associated with deficiency of the von Willebrand factor-cleaving protease, ADAMTS13, and its inhibitor. Low ADAMTS13 activity is present in most of idiopathic TTP patients. The prognosis of TTP was improved by plasma exchange treatment, which replaces the ADAMTS13 and removes ADAMTS13 inhibitor. However, ADAMTS13 activity is normal in some TTP patients. These are found among the secondary TTP patients associated with collagen disease, hematopoietic stem cell transplantation, malignancy, or drugs. In addition, most of them do not respond to plasma exchange. On the other hand, several reports demonstrated that rituximab, which is an anti-CD20 monoclonal antibody, is effective for refractory TTP cases caused by ADAMTS13 deficiency. It is considered that the effect of rituximab is associated with disappearance of ADAMTS13 inhibitor. However, rituximab therapy was effective for the TTP patients with normal ADAMTS13 activity in our cases. We considered another mechanism of rituximab for TTP cases.
authors.affiliation: Department of Internal Medicine, Division of Endocrinology and Metabolism, Hematology, Rheumatology and Respiratory Medicine, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kameda
authors.affiliation: Department of Internal Medicine, Division of Endocrinology and Metabolism, Hematology, Rheumatology and Respiratory Medicine, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan. hdobashi@med.kagawa-u.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Dobashi
authors.affiliation: Department of Internal Medicine, Division of Endocrinology and Metabolism, Hematology, Rheumatology and Respiratory Medicine, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan.
authors.forename: Katsuharu
authors.initials: K
authors.lastname: Kittaka
authors.affiliation: Department of Internal Medicine, Division of Endocrinology and Metabolism, Hematology, Rheumatology and Respiratory Medicine, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Susaki
authors.affiliation: Department of Clinical Laboratory, Kagawa University Hospital, Kagawa, Japan.
authors.forename: Genji
authors.initials: G
authors.lastname: Yamaoka
authors.affiliation: Department of Clinical Laboratory, Kagawa University Hospital, Kagawa, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Arai
authors.affiliation: Sanuki Municipal Hospital, Sanuki, Japan.
authors.forename: Michiaki
authors.initials: M
authors.lastname: Tokuda
authors.affiliation: Department of Internal Medicine, Division of Endocrinology and Metabolism, Hematology, Rheumatology and Respiratory Medicine, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ishida
mesh_terms: D051722:ADAM Proteins / Q000097:blood; D000071120:ADAMTS13 Protein; D000328:Adult; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D003095:Collagen Diseases / Q000150:complications* / Q000188:drug therapy; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007155:Immunologic Factors / Q000627:therapeutic use*; D011697:Purpura, Thrombotic Thrombocytopenic / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology*; D000069283:Rituximab; D014841:von Willebrand Factor
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D007155:Immunologic Factors; D014841:von Willebrand Factor; D000069283:Rituximab; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human