Polyclonal autoantibodies against C1 inhibitor in a case of acquired angioedema.
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.
Ponce
Isabel M
IM
Immunology Unit, Hospital Universitario La Paz, Madrid, Spain.
Caballero
Teresa
T
Reche
Marta
M
Piteiro
Ana B
AB
López-Serrano
M Concepción
MC
Fontán
Gumersindo
G
López-Trascasa
Margarita
M
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
D000888:Antibodies, Anti-Idiotypic; D000933:Antifibrinolytic Agents; D001323:Autoantibodies; D003172:Complement C1; D003174:Complement C1 Inactivator Proteins; D007074:Immunoglobulin G; C048844:anti-IgG