Smith CJA, Bensing S, Burns C, Robinson PJ, Kasperlik-Zaluska AA, Scott RJ, Kämpe O, Crock PA. Identification of TPIT and other novel autoantigens in lymphocytic hypophysitis: immunoscreening of a pituitary cDNA library and development of immunoprecipitation assays.
Eur J Endocrinol 2012;
166:391-8. [PMID:
22193973 PMCID:
PMC3290121 DOI:
10.1530/eje-11-1015]
[Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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.
DESIGN/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.
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