title: Plasma cells within granulomatous inflammation display signs pointing to autoreactivity and destruction in granulomatosis with polyangiitis.
abstract: BACKGROUND
  Plasma cells residing in inflamed tissues produce antibodies in chronic inflammatory and systemic autoimmune diseases. This study examined if plasma cells, located within inflamed nasal tissue in granulomatosis with polyangiitis (GPA), express features potentially associated with the autoimmune and destructive character of this disease.
  
  
  METHODS
  Ig gene mutation patterns of individual tissue-derived plasma cells from GPA (n = 5) were analyzed, by using laser-assisted microdissection followed by semi-nested polymerase chain reaction (PCR). Signs of B-lymphocyte maturation (ectopic lymphoid structures, ELS) and survival (a proliferation-inducing ligand, APRIL; B-cell maturation antigen, BCMA; transmembrane-activator and calcium modulator and cyclophilin interactor, TACI; receptor activator of nuclear factor κB ligand, RANKL) were examined in nasal tissues or serum, respectively, by using immunohistochemistry/fluorescence and enzyme-linked immunosorbent assay, ELISA.
  
  
  RESULTS
  Plasma-cell derived Ig genes (light- and heavy-chain pairs, n = 4; heavy chains, n = 33) resembled mutation patterns seen in other autoimmune diseases, predominantly displaying selection against replacement mutations within the framework region of Ig genes (10 of 15), which is responsible for structural integrity. Ectopic lymphoid structures were similar between GPA and a disease control (that is, unspecific chronic rhinosinusitis. However, histomorphologic features distinguishing GPA from rhinosinusitis (that is, neutrophilic microabscess and granuloma) expressed considerable amounts of membrane-associated and secreted APRIL, respectively. The latter was co-localized with CD138 and found in close proximity to cells expressing IgG, TACI, and BCMA. Interestingly, plasma cells strongly expressed receptor activator of nuclear factor κB ligand (RANKL), apart from fibroblast-like cells.
  
  
  CONCLUSIONS
  Plasma cells within granulomatous inflammation appear to display features that might be required for autoreactivity and, possibly, RANKL-mediated destruction in GPA.
authors.forename: Antje
authors.initials: A
authors.lastname: Mueller
authors.forename: Christoph
authors.initials: C
authors.lastname: Brieske
authors.forename: Susanne
authors.initials: S
authors.lastname: Schinke
authors.forename: Elena
authors.initials: E
authors.lastname: Csernok
authors.forename: Wolfgang L
authors.initials: WL
authors.lastname: Gross
authors.forename: Katrin
authors.initials: K
authors.lastname: Hasselbacher
authors.forename: Jan
authors.initials: J
authors.lastname: Voswinkel
authors.forename: Konstanze
authors.initials: K
authors.lastname: Holl-Ulrich
mesh_terms: D015551:Autoimmunity / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005803:Genes, Immunoglobulin / Q000235:genetics; D014890:Granulomatosis with Polyangiitis / Q000235:genetics / Q000276:immunology* / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000276:immunology* / Q000473:pathology; D061346:Laser Capture Microdissection; D010950:Plasma Cells / Q000276:immunology* / Q000473:pathology; D016133:Polymerase Chain Reaction