Anti–Factor H Autoantibodies Associated with Atypical... : Journal of the American Society of Nephrology (original) (raw)

Clinical Immunology and Pathology

Anti–Factor H Autoantibodies Associated with Atypical Hemolytic Uremic Syndrome

Dragon-Durey, Marie-Agne[Combining Grave Accent]s*; Loirat, Chantal†; Cloarec, Sylvie‡; Macher, Marie-Alice†; Blouin, Jacques*; Nivet, Hubert‡; Weiss, Laurence§; Fridman, Wolf Herman*, ‖; Frémeaux-Bacchi, Véronique*, ‖

*Service d’Immunologie Biologique, Ho[Combining Circumflex Accent]pital Européen Georges Pompidou, Assistance Publique-Ho[Combining Circumflex Accent]pitaux de Paris, Paris; †Service de Néphrologie, Ho[Combining Circumflex Accent]pital Robert Debré, Assistance Publique-Ho[Combining Circumflex Accent]pitaux de Paris, Paris; ‡Unité de Néphrologie Pédiatrique, Centre Hospitalier de Tours, Tours; §Service d’Immunologie Clinique, Ho[Combining Circumflex Accent]pital Européen Georges Pompidou, Assistance Publique-Ho[Combining Circumflex Accent]pitaux de Paris, Paris; and ‖INSERM U255, Institut des Cordeliers, Paris, France

Address correspondence to: Dr. Marie-Agne[Combining Grave Accent]s Dragon-Durey, Service d’Immunologie Biologique, Ho[Combining Circumflex Accent]pital Européen Georges Pompidou, 20 rue Leblanc, 75 015 Paris, France. Phone: 33-1-56-09-39-41; Fax: 33-1-56-09-20-80; E-mail: [email protected]

Accepted October 22, 2004

Received May 12, 2004

Abstract

Several studies have demonstrated genetic predisposition in non–shigatoxin-associated hemolytic uremic syndrome (HUS), involving regulatory proteins of the complement alternative pathway: Factor H (FH) and membrane co-factor protein (CD46). Regarding the observations of thrombotic thrombocytopenic purpura patients, in whom a von Willebrand factor protease (ADAMST-13) deficiency may be inherited or acquired secondary to IgG antibodies, it was speculated that HUS might occur in a context of an autoimmune disease with the development of anti-FH antibodies leading to an acquired FH deficiency. The presence of FH autoantibodies was investigated by an ELISA method using coated purified human FH in a series of 48 children who presented with atypical HUS and were recruited from French university hospitals. Anti-FH IgG antibodies were detected in the plasma of three children who presented with recurrent HUS. The anti-FH specificity was conserved by the Fab′2 fraction. The plasma FH activity was found to be decreased, whereas plasma FH antigenic levels and FH gene analysis were normal, indicating that the presence of anti-FH antibodies led to an acquired functional FH deficiency. This report supports for the first time that HUS may occur in a context of an autoimmune disease with the development of anti-FH–specific antibody leading to an acquired FH deficiency. This new mechanism of functional FH deficiency may lead to the design of new approaches of diagnosis and treatment with a particular interest in plasma exchanges or immunosuppressive therapies.