HLA-B7–Restricted Islet Epitopes Are Differentially Recognized in Type 1 Diabetic Children and Adults and Form Weak Peptide-HLA Complexes
- Matthieu Scotto1,2,
- Georgia Afonso1,2,
- Thomas Østerbye3,
- Etienne Larger2,4,
- Sandrine Luce1,2,
- Cécile Raverdy5,6,
- Giulia Novelli7,
- Graziella Bruno7,
- Céline Gonfroy-Leymarie4,
- Odile Launay8,
- François A. Lemonnier1,2,
- Søren Buus3,
- Jean-Claude Carel5,6,
- Christian Boitard1,2,4 and
- Roberto Mallone1,2,4⇓
- 1INSERM, U986, DeAR Lab Avenir, Cochin-Saint Vincent de Paul Hospital, Paris, France
- 2Faculté de Médecine, Paris Descartes University, Sorbonne Paris Cité, Paris, France
- 3Laboratory of Experimental Immunology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
- 4Department of Diabetology, Cochin-Hôtel Dieu Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
- 5Department of Pediatric Endocrinology and Diabetes, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
- 6Paris 7 Denis Diderot University, Paris, France
- 7Departement of Internal Medicine, University of Turin, Turin, Italy
- 8INSERM, CIC BT505, Centre d’Investigation Clinique de Vaccinologie Cochin Pasteur, Cochin-Hôtel Dieu Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
- Corresponding author: Roberto Mallone, .
The cartography of β-cell epitopes targeted by CD8+ T cells in type 1 diabetic (T1D) patients remains largely confined to the common HLA-A2 restriction. We aimed to identify β-cell epitopes restricted by the HLA-B7 (B*07:02) molecule, which is associated with mild T1D protection. Using DNA immunization on HLA-B7–transgenic mice and prediction algorithms, we identified GAD and preproinsulin candidate epitopes. Interferon-γ (IFN-γ) enzyme-linked immunospot assays on peripheral blood mononuclear cells showed that most candidates were recognized by new-onset T1D patients, but not by type 2 diabetic and healthy subjects. Some epitopes were highly immunodominant and specific to either T1D children (GAD530–538; 44% T cell–positive patients) or adults (GAD311–320; 38%). All epitopes displayed weak binding affinity and stability for HLA-B7 compared with HLA-A2–restricted ones, a general feature of HLA-B7. Single-cell PCR analysis on β-cell–specific (HLA-B7 tetramer–positive) T cells revealed uniform IFN-γ and transforming growth factor-β (TGF-β) mRNA expression, different from HLA-A2–restricted T cells. We conclude that HLA-B7–restricted islet epitopes display weak HLA-binding profiles, are different in T1D children and adults, and are recognized by IFN-γ+TGF-β+CD8+ T cells. These features may explain the T1D-protective effect of HLA-B7. The novel epitopes identified should find valuable applications for immune staging of HLA-B7+ individuals.
This article contains Supplementary Data online at http://diabetes.diabetesjournals.org/lookup/suppl/doi:10.2337/DB12-0136/-/DC1.
- Received February 8, 2012.
- Accepted April 10, 2012.
- © 2012 by the American Diabetes Association.
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