title: Evaluation of Autoantibodies in Patients with Primary and Secondary Sjogren's Syndrome.
abstract: BACKGROUND
  Antibodies to salivary gland protein 1 (SP1), carbonic anhydrase 6 (CA6) and parotid secretory protein (PSP) were discovered in an animal model of Sjogren's syndrome (SS). Their expression was noted in patients with SS, especially those with lower focus scores on lip biopsies and those with early disease lacking antibodies to Ro and La.
  
  
  OBJECTIVE
  The current studies evaluated these autoantibodies in patients with long-standing SS expressing high levels of anti-Ro antibodies and in patients with Sjogren's syndrome secondary to systemic lupus erythematosus (SLE), systemic sclerosis (SSc) and mixed connective tissue disease (MCTD).
  
  
  METHODS
  Sera were obtained from patients and evaluated by ELISA for IgG, IgA and IgM antibodies to SP1, CA6 and PSP.
  
  
  RESULTS
  IgA anti-CA6 antibodies were noted in 38% of these patients, but anti-SP1, CA6 and PSP IgM or IgG antibodies were identified only in a minority of patients. In patients with secondary SS, antibodies to SP1/CA6/PSP were more sensitive and specific than anti-Ro .
  
  
  CONCLUSIONS
  While more studies are needed, antibodies to SP1, CA6 and PSP provide valuable markers for the diagnosis of primary and secondary SS, especially early in the course of the disease.
authors.affiliation: Department of Rheumatology, University Hospital Leuven, Herestraat 49, 3000 Leuven, Belgium.
authors.forename: Ellen
authors.initials: E
authors.lastname: De Langhe
authors.affiliation: Laboratory Medicine, University Hospitals Leuven, Belgium and Department of Microbiology and Immunology KU Leuven, Belgium.
authors.forename: Xavier
authors.initials: X
authors.lastname: Bossuyt
authors.affiliation: Immco Diagnostics / Trinity Biotech, Buffalo, NY, USA.
authors.forename: Long
authors.initials: L
authors.lastname: Shen
authors.affiliation: Immco Diagnostics / Trinity Biotech, Buffalo, NY, USA.
authors.forename: Kishore
authors.initials: K
authors.lastname: Malyavantham
authors.affiliation: Division of Allergy, Immunology and Rheumatology, SUNY at Buffalo School of Medicine, Buffalo, NY, USA.
authors.forename: Julian L
authors.initials: JL
authors.lastname: Ambrus
authors.affiliation: Immco Diagnostics / Trinity Biotech, Buffalo, NY, USA; Department of Oral Diagnostic Sciences, SUNY at Buffalo School of Dental Medicine, Buffalo, NY, USA.
authors.forename: Lakshmanan
authors.initials: L
authors.lastname: Suresh
keywords: MCTD; SLE; Sjogren’s syndrome; Systemic Sclerosis