title: Immunology of Diabetes Society T-Cell Workshop: HLA class II tetramer-directed epitope validation initiative.
abstract: BACKGROUND
  Islet-antigen-specific CD4+ T cells are known to promote auto-immune destruction in T1D. Measuring T-cell number and function provides an important biomarker. In response to this need, we evaluated responses to proinsulin and GAD epitopes in a multicentre study.
  
  
  METHODS
  A tetramer-based assay was used in five participating centres to measure T-cell reactivities to DR0401-restricted epitopes. Three participating centres concurrently performed ELISPOT or immunoblot assays. Each centre used blind-coded, centrally distributed peptide and tetramer reagents.
  
  
  RESULTS
  All participating centres detected responses to auto-antigens and the positive control antigen, and in some cases cloned the corresponding T cells. However, response rates varied among centres. In total, 74% of patients were positive for at least one islet epitope. The most commonly recognized epitope was GAD270-285. Only a minority of the patients tested by tetramer and ELISPOT were concordant for both assays.
  
  
  CONCLUSIONS
  This study successfully detected GAD and proinsulin responses using centrally distributed blind-coded reagents. Centres with little previous experience using class II tetramer reagents implemented the assay. The variability in response rates observed for different centres suggests technical difficulties and/or heterogeneity within the local patient populations tested. Dual analysis by tetramer and ELISPOT or immunoblot assays was frequently discordant, suggesting that these assays detect distinct cell populations. Future efforts should investigate shared blood samples to evaluate assay reproducibility and longitudinal samples to identify changes in T-cell phenotype that correlate with changes in disease course.
authors: Benaroya Research Institute, Seattle, WA 98101, USA.
authors: E A
authors: EA
authors: James
authors: R
authors: R
authors: Mallone
authors: N C
authors: NC
authors: Schloot
authors: M C
authors: MC
authors: Gagnerault
authors: J
authors: J
authors: Thorpe
authors: L
authors: L
authors: Fitzgerald-Miller
authors: J
authors: J
authors: Reichow
authors: R
authors: R
authors: Wagner
authors: M N
authors: MN
authors: Pham
authors: N
authors: N
authors: Jospe
authors: O
authors: O
authors: Lou
authors: P A
authors: PA
authors: Gottlieb
authors: B M
authors: BM
authors: Brooks-Worrell
authors: Ivana
authors: I
authors: Durinovic-Belló
mesh_terms: D000328:Adult; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D058501:Enzyme-Linked Immunospot Assay; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D006684:HLA-DR Antigens / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D011384:Proinsulin / Q000276:immunology
chemical_list: D018984:Epitopes, T-Lymphocyte; D006684:HLA-DR Antigens; D000949:Histocompatibility Antigens Class II; D011384:Proinsulin