title: Immunoglobulin deposition disease with a membranous pattern and a circulating monoclonal immunoglobulin G with charge-dependent aggregation properties.
abstract: A 62-year-old woman presented with nephrotic syndrome, monoclonal gammopathy, and membranous-like nephropathy with nonorganized deposits composed of monoisotypic immunoglobulin G1 lambda protein. Nephrotic syndrome remitted after a brief course of treatment with melphalan despite ongoing production of the monoclonal protein. The circulating monoclonal immunoglobulin G1 lambda showed unusual in vitro aggregation properties, including dependence on low ionic strength and neutral pH, suggesting that electrostatic interactions had a role in the precipitation process. This case illustrates the importance of looking for monoclonal immunoglobulin deposits when kidney biopsy findings are suggestive of membranous nephropathy. In addition, our in vitro demonstrations of the role of physicochemical factors in immunoglobulin precipitation help elucidate the pathogenesis of immunoglobulin deposition disorders. Although binding to podocyte antigens is a well-recognized determinant of subepithelial immunoglobulin deposition, proneness to aggregation as described in this case also might be nephritogenic.
authors.affiliation: AP-HP, Hôpital Tenon, Service de Néphrologie et Dialyses, Paris, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: de Seigneux
authors.forename: Pascal
authors.initials: P
authors.lastname: Bindi
authors.forename: Hanna
authors.initials: H
authors.lastname: Debiec
authors.forename: Marie-Alexandra
authors.initials: MA
authors.lastname: Alyanakian
authors.forename: Bernadette
authors.initials: B
authors.lastname: Aymard
authors.forename: Patrice
authors.initials: P
authors.lastname: Callard
authors.forename: Pierre
authors.initials: P
authors.lastname: Ronco
authors.forename: Pierre
authors.initials: P
authors.lastname: Aucouturier
mesh_terms: D005260:Female; D015433:Glomerulonephritis, Membranous / Q000097:blood* / Q000175:diagnosis*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008875:Middle Aged; D008998:Monoclonal Gammopathy of Undetermined Significance / Q000097:blood* / Q000175:diagnosis*; D010265:Paraproteinemias / Q000097:blood / Q000175:diagnosis
chemical_list: D007074:Immunoglobulin G