title: Phospholipase A2 Receptor-Related Membranous Nephropathy and Mannan-Binding Lectin Deficiency.
abstract: Most patients with idiopathic membranous nephropathy (IMN) have IgG4 autoantibodies against phospholipase A2 receptor (PLA2R). C3 and C5b-9 are found in immune deposits of IMN kidney biopsy specimens, but the pathway of complement activation in IMN remains elusive. We report the case of a patient who developed IMN with intense staining for PLA2R, IgG4, C3, C5b-9, factor B, and properdin and very weak staining for C1q, C4d, and IgG1. Measurement of mannan binding lectin (MBL) antigenic level and activity revealed MBL deficiency. Genotyping revealed a heterozygous (A/C) polymorphism in codon 57 of MBL2 exon 1 associated with homozygous and heterozygous variations in the promoter region at -550 (L/L) and -221 (X/Y), respectively, suggesting that the patient harbored the LXA/LYC haplotypes linked to MBL deficiency. Genetic sequencing in 77 consecutive patients with IMN identified four patients with MBL2 promoter and coding region variations associated with MBL deficiency and the same complement pattern in immune deposits as the index patient. In contrast, patients with wild-type MBL2 had immune deposits with intense Cd4 staining. Thus, IMN can develop in patients with complete MBL deficiency, with complement activated mainly by the alternative pathway, whereas the lectin pathway is also activated in those with wild-type MBL2.
authors.affiliation: Service de Néphrologie Dialyse, Centre Hospitalier Métropole Savoie, Chambery, France; stephane.bally@ch-metropole-savoie.fr hanna.debiec@upmc.fr.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Bally
authors.affiliation: Sorbonne Universités, Universitè Pierre and Marie Curie University, Paris 06, Paris, France; stephane.bally@ch-metropole-savoie.fr hanna.debiec@upmc.fr.|Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche UMR_S1155, Paris, France.
authors.forename: Hanna
authors.initials: H
authors.lastname: Debiec
authors.affiliation: Laboratoire d'Immunologie, Pôle de Biologie, Centre Hospitalier Universitalier de Grenoble, Grenoble, France.
authors.forename: Denise
authors.initials: D
authors.lastname: Ponard
authors.affiliation: Centre de Pathologie Est, Hôpitaux de Lyon, Bron, France.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Dijoud
authors.affiliation: Département de Biochimie Pharmacologie, Biochimie et Génétique Moléculaire, Université de Grenoble Alpes Grenoble, France; and.
authors.forename: John
authors.initials: J
authors.lastname: Rendu
authors.affiliation: Département de Biochimie Pharmacologie, Biochimie et Génétique Moléculaire, Université de Grenoble Alpes Grenoble, France; and.
authors.forename: Julien
authors.initials: J
authors.lastname: Fauré
authors.affiliation: Sorbonne Universités, Universitè Pierre and Marie Curie University, Paris 06, Paris, France.|Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche UMR_S1155, Paris, France.|Assistance Publique-Hôpitaux de Paris, Néphrologie et Dialyses, Hôpital Tenon, Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Ronco
authors.affiliation: Laboratoire d'Immunologie, Pôle de Biologie, Centre Hospitalier Universitalier de Grenoble, Grenoble, France.
authors.forename: Chantal
authors.initials: C
authors.lastname: Dumestre-Perard
mesh_terms: D000328:Adult; D015433:Glomerulonephritis, Membranous / Q000209:etiology* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008297:Male; D037601:Mannose-Binding Lectin / Q000172:deficiency* / Q000235:genetics; D054507:Receptors, Phospholipase A2 / Q000502:physiology*
chemical_list: D037601:Mannose-Binding Lectin; D054507:Receptors, Phospholipase A2
keywords: complement; glomerular disease; immunohistochemistry; membranous nephropathy