title: Identification of TPIT and other novel autoantigens in lymphocytic hypophysitis: immunoscreening of a pituitary cDNA library and development of immunoprecipitation assays.
abstract: BACKGROUND
  Lymphocytic hypophysitis is an organ-specific autoimmune disease of the pituitary gland. A specific and sensitive serological test currently does not exist to aid in the diagnosis.
  
  
  OBJECTIVE
  To identify target autoantigens in lymphocytic hypophysitis and develop a diagnostic assay for these proteins.
  
  
  METHODS
  A pituitary cDNA expression library was immunoscreened using sera from four patients with lymphocytic hypophysitis. Relevant cDNA clones from screening, along with previously identified autoantigens pituitary gland-specific factor 1a and 2 (PGSF1a and PGSF2) and neuron-specific enolase (NSE) were tested in an in vitro transcription and translation immunoprecipitation assay. The corticotroph-specific transcription factor, TPIT, was investigated separately as a candidate autoantigen.
  
  
  RESULTS
  Significantly positive autoantibody reactivity against TPIT was found in 9/86 hypophysitis patients vs 1/90 controls (P = 0.018). The reactivity against TPIT was not specific for lymphocytic hypophysitis with autoantibodies detectable in the sera from patients with other autoimmune endocrine diseases. Autoantibodies were also detected against chromodomain-helicase-DNA binding protein 8, presynaptic cytomatrix protein (piccolo), Ca(2+)-dependent secretion activator, PGSF2 and NSE in serum samples from patients with lymphocytic hypophysitis, but at a frequency that did not differ from healthy controls. Importantly, 8/86 patients with lymphocytic hypophysitis had autoantibodies against any two autoantigens in comparison with 0/90 controls (P = 0.0093).
  
  
  CONCLUSIONS
  TPIT, a corticotroph-specific transcription factor, was identified as a target autoantigen in 10.5% of patients with lymphocytic hypophysitis. Further autoantigens related to vesicle processing were also identified as potential autoantigens with different immunoreactivity patterns in patients and controls.
authors.affiliation: Department of Paediatric Endocrinology and Diabetes, Faculty of Health, Locked Bag 1, Newcastle Mail Centre, John Hunter Children's Hospital, University of Newcastle, Newcastle 2310, New South Wales, Australia.
authors.forename: Casey Jo Anne
authors.initials: CJ
authors.lastname: Smith
authors.forename: Sophie
authors.initials: S
authors.lastname: Bensing
authors.forename: Christine
authors.initials: C
authors.lastname: Burns
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Robinson
authors.forename: Anna A
authors.initials: AA
authors.lastname: Kasperlik-Zaluska
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Scott
authors.forename: Olle
authors.initials: O
authors.lastname: Kämpe
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Crock
mesh_terms: D001323:Autoantibodies / Q000096:biosynthesis; D001324:Autoantigens / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D001327:Autoimmune Diseases / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D015723:Gene Library; D018398:Homeodomain Proteins / Q000235:genetics* / Q000276:immunology; D006801:Humans; D007018:Hypopituitarism / Q000175:diagnosis / Q000235:genetics* / Q000276:immunology; D047468:Immunoprecipitation / Q000379:methods; D010902:Pituitary Gland / Q000276:immunology / Q000473:pathology; D020825:T-Box Domain Proteins / Q000235:genetics* / Q000276:immunology
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D018398:Homeodomain Proteins; D020825:T-Box Domain Proteins; C486589:TBX19 protein, human