title: IgG4 as the predominant IgG subclass in pemphigoides gestationis.
abstract: BACKGROUND
  Pemphigoides gestationis (PG) is a blistering disorder of pregnancy caused by antibodies against basement membrane proteins. They are directed against the 180 kD bullous pemphigoid antigen (BPAg2), towards the epitopes within the NC 16A domain. There are many similarities between pemphigoid gestationis and bullous pemphigoid (BP), but the literature so far indicated different immunofluorescence results in regards with C3 and IgG, and IgG subclasses (IgG4 vs. IgG1).
  
  
  METHODS
  We evaluated staining patterns and IgG subclasses, as well as C5b-9 membrane attack complex (MAC) in 10 pregnant patients with PG, using sandwich double antibody immunofluorescence (SDAI) and direct immunofluorescence (DIF).
  
  
  RESULTS
  All ten specimens stained with C3 by DIF, but only five had trace amount of IgG reactants by this method. By SDAI, 100% were positive for the IgG4 and C5b-9 MAC, 70% for IgG2, 50% for IgG1, and 40% for IgG3.
  
  
  CONCLUSIONS
  IgG4 was the predominant IgG subtype identified. This finding has not been reported for PG, but it mimics results reported for BP. One explanation is prolonged disease course, as well as blocking of antigenic domains by IgG4. Understanding this completely will help develop therapies and prevention strategies for immunobullous and other autoimmune diseases, and perhaps aid in an exact classification.
authors.affiliation: Department of Dermatology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: T
authors.initials: T
authors.lastname: Patton
authors.forename: R W
authors.initials: RW
authors.lastname: Plunkett
authors.forename: E H
authors.initials: EH
authors.lastname: Beutner
authors.forename: J S
authors.initials: JS
authors.lastname: Deng
authors.forename: D M
authors.initials: DM
authors.lastname: Jukic
mesh_terms: D015938:Complement Membrane Attack Complex / Q000032:analysis; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D006559:Pemphigoid Gestationis / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D011247:Pregnancy; D013194:Staining and Labeling
chemical_list: D015938:Complement Membrane Attack Complex; D007074:Immunoglobulin G