title: Autoimmune C1 inhibitor deficiency: report of eight patients.
abstract: OBJECTIVE
  In this study, we investigated the clinical and biochemical features and the responses to treatment of eight patients with auto-antibody-mediated C1 inhibitor (C1-INH) deficiency and symptoms of angioedema.
  
  
  METHODS
  In addition to the 8 patients with acquired angioedema (AAE), we also studied 36 subjects with hereditary angioedema (HAE), 15 of them treated with C1-INH plasma concentrate, and 26 patients with different autoantibodies in their plasma (10 with systemic lupus erythematosus, 6 with lupus-like anticoagulant, and 10 with chronic liver disease). Functional C1-INH was measured with the reagent kit of Immuno (Vienna, Austria); C1-INH, C4, and C1q antigen were determined by radial immunodiffusion; and autoantibodies to C1-INH were detected by an enzyme-linked immunosorbent assay method.
  
  
  RESULTS
  Four patients with AAE had no other diseases, one had breast cancer, one liver hydatidosis, one Waldenström's disease, and one a benign M component. Functional C1-INH levels were below 30% of normal, and C1q plasma levels were low in seven patients but normal in one. Autoantibodies to C1-INH were detectable in all eight AAE patients but in none of the others. Prophylactic treatment with attenuated androgens was successful in one of four patients, and with antifibrinolytic agents (tranexamic acid) in six of seven patients. Laryngeal attacks in five patients were treated with C1-INH plasma concentrate; two patients had marked clinical and biochemical responses. In three, the symptoms resolved only with high doses, and the biochemical parameters did not significantly increase.
  
  
  CONCLUSIONS
  Our results suggest that patients with autoimmune AAE are clinically and biochemically heterogeneous. They have different responses to treatment that seem to be related to variable C1-INH consumption.
authors.affiliation: Clinica Medica III, Università di Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cicardi
authors.forename: G
authors.initials: G
authors.lastname: Bisiani
authors.forename: M
authors.initials: M
authors.lastname: Cugno
authors.forename: P
authors.initials: P
authors.lastname: Späth
authors.forename: A
authors.initials: A
authors.lastname: Agostoni
mesh_terms: D000368:Aged; D000799:Angioedema / Q000097:blood* / Q000175:diagnosis / Q000276:immunology / Q000628:therapy; D017151:Antibodies, Catalytic / Q000097:blood*; D001323:Autoantibodies / Q000097:blood*; D001327:Autoimmune Diseases / Q000097:blood* / Q000175:diagnosis / Q000276:immunology / Q000628:therapy; D003174:Complement C1 Inactivator Proteins / Q000172:deficiency* / Q000627:therapeutic use; D015922:Complement C1q / Q000032:analysis; D003181:Complement C4 / Q000032:analysis; D003613:Danazol / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013197:Stanozolol / Q000627:therapeutic use
chemical_list: D017151:Antibodies, Catalytic; D001323:Autoantibodies; D003174:Complement C1 Inactivator Proteins; D003181:Complement C4; D013197:Stanozolol; D015922:Complement C1q; D003613:Danazol