title: Polyclonal autoantibodies against C1 inhibitor in a case of acquired angioedema.
abstract: BACKGROUND
  Angioedema attributable to acquired C1 inhibitor (C1-INH) deficiency is a rare disease related to lymphoproliferative disorders or autoantibodies to Cl inhibitor. We describe a patient with angioedema and autoantibodies to C1 inhibitor.
  
  
  OBJECTIVE
  To study the characteristics of autoantibodies to C1-INH in a patient with acquired angioedema.
  
  
  METHODS
  Autoantibodies to Cl-INH were measured by enzyme-linked immunoadsorbent assay. Immunoglobulin (Ig)G autoantibody was purified by affinity chromatography on a protein G agarose column. We developed an enzyme-linked immunoadsorbent assay to determine whether the autoantibodies were directed against the C1-INH active center.
  
  
  RESULTS
  IgM and mainly C1-INH IgG autoantibodies were detected; both had kappa and lambda chains. No monoclonal component was detected. The autoantibodies were directed against the Cl-INH active center. After various treatment strategies were attempted, an effective clinical response was attained with antifibrinolytic therapy.
  
  
  CONCLUSIONS
  A case of acquired angioedema because of C1-INH deficiency was found to be attributable to the presence of polyclonal autoantibodies to C1-INH.
authors.affiliation: Immunology Unit, Hospital Universitario La Paz, Madrid, Spain.
authors.forename: Isabel M
authors.initials: IM
authors.lastname: Ponce
authors.forename: Teresa
authors.initials: T
authors.lastname: Caballero
authors.forename: Marta
authors.initials: M
authors.lastname: Reche
authors.forename: Ana B
authors.initials: AB
authors.lastname: Piteiro
authors.forename: M Concepción
authors.initials: MC
authors.lastname: López-Serrano
authors.forename: Gumersindo
authors.initials: G
authors.lastname: Fontán
authors.forename: Margarita
authors.initials: M
authors.lastname: López-Trascasa
mesh_terms: D000368:Aged; D000799:Angioedema / Q000188:drug therapy / Q000209:etiology / Q000276:immunology*; D000888:Antibodies, Anti-Idiotypic / Q000032:analysis; D000933:Antifibrinolytic Agents / Q000627:therapeutic use; D001323:Autoantibodies / Q000032:analysis*; D003172:Complement C1 / Q000276:immunology; D003174:Complement C1 Inactivator Proteins / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D008297:Male
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000933:Antifibrinolytic Agents; D001323:Autoantibodies; D003172:Complement C1; D003174:Complement C1 Inactivator Proteins; D007074:Immunoglobulin G; C048844:anti-IgG