title: Anti-Factor H autoantibodies associated with atypical hemolytic uremic syndrome.
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.
authors.affiliation: Service d'Immunologie Biologique, Hôpital Européen Georges Pompidou, 20 rue Leblanc, 75015 Paris, France. marie-agnes.durey@egp.ap-hop-paris.fr
authors.forename: Marie-Agnès
authors.initials: MA
authors.lastname: Dragon-Durey
authors.forename: Chantal
authors.initials: C
authors.lastname: Loirat
authors.forename: Sylvie
authors.initials: S
authors.lastname: Cloarec
authors.forename: Marie-Alice
authors.initials: MA
authors.lastname: Macher
authors.forename: Jacques
authors.initials: J
authors.lastname: Blouin
authors.forename: Hubert
authors.initials: H
authors.lastname: Nivet
authors.forename: Laurence
authors.initials: L
authors.lastname: Weiss
authors.forename: Wolf Herman
authors.initials: WH
authors.lastname: Fridman
authors.forename: Véronique
authors.initials: V
authors.lastname: Frémeaux-Bacchi
mesh_terms: D017677:Age Distribution; D001323:Autoantibodies / Q000032:analysis / Q000276:immunology*; D015415:Biomarkers / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D017242:Complement Factor H / Q000276:immunology*; D005260:Female; D005602:France / Q000453:epidemiology; D006463:Hemolytic-Uremic Syndrome / Q000453:epidemiology* / Q000276:immunology*; D006801:Humans; D015994:Incidence; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D017678:Sex Distribution; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; C493495:CFH protein, human; D014841:von Willebrand Factor; D017242:Complement Factor H