title: Distribution of glomerular IgG subclass deposits in patients with membranous nephropathy and anti-U1 ribonucleoprotein antibody.
abstract: BACKGROUND
  It is known that a predominant glomerular deposition of IgG4 is characteristic of idiopathic membranous nephropathy (MN) and that significant deposition of other IgG subclasses is also observed in lupus MN. However, there is no report focusing on the distribution of glomerular IgG subclass deposits in MN patients with anti-U1 ribonucleoprotein (RNP) antibody.
  
  
  METHODS
  We evaluated clinicopathological features and the distribution patterns of glomerular IgG subclass deposits in seven MN patients with positive anti-RNP antibody and negative antibodies to double-stranded DNA (dsDNA) and Smith antigen (Sm) (RNP-MN group) and in seven age- and sex-matched lupus MN patients with positive anti-dsDNA antibody and negative antibodies to RNP and Sm (L-MN group).
  
  
  RESULTS
  Mixed connective tissue disease was diagnosed in four patients in the RNP-MN group. Two patients in the RNP-MN group and three patients in the L-MN group developed nephrotic syndrome. Renal insufficiency was not present in all patients in both groups. Hypocomplementemia was found in two patients in the RNP-MN group and six patients in the L-MN group. In the RNP-MN group, positive stainings for glomerular IgG1, IgG2, IgG3 and IgG4 were observed in one, seven, zero and five patients, respectively. On the contrary, in the L-MN group, positive stainings for glomerular IgG1, IgG2, IgG3 and IgG4 were observed in seven, seven, seven, and six patients, respectively.
  
  
  CONCLUSIONS
  This is the first study showing striking differences in the distribution of glomerular IgG subclass deposits between RNP-MN and L-MN groups. RNP-MN and L-MN may result from different immunological mechanisms.
authors.affiliation: Department of Hematology, Nephrology and Rheumatology, Akita University Graduate School of Medicine, Akita, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Omokawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Komatsuda
authors.forename: Mizuho
authors.initials: M
authors.lastname: Nara
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fujiwara
authors.forename: Ryuta
authors.initials: R
authors.lastname: Sato
authors.forename: Masaru
authors.initials: M
authors.lastname: Togashi
authors.forename: Shin
authors.initials: S
authors.lastname: Okuyama
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Sawada
authors.forename: Hideki
authors.initials: H
authors.lastname: Wakui
mesh_terms: D000328:Adult; D000368:Aged; D000888:Antibodies, Anti-Idiotypic / Q000378:metabolism*; D016022:Case-Control Studies; D004247:DNA / Q000276:immunology; D003937:Diagnosis, Differential; D005260:Female; D015433:Glomerulonephritis, Membranous / Q000175:diagnosis / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007074:Immunoglobulin G / Q000145:classification* / Q000378:metabolism*; D007678:Kidney Glomerulus / Q000276:immunology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000276:immunology*
chemical_list: D000888:Antibodies, Anti-Idiotypic; D007074:Immunoglobulin G; D017412:Ribonucleoprotein, U1 Small Nuclear; D004247:DNA