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- Title
Epitope Stealing as a Mechanism of Dominant Protection by HLA-DQ6 in Type 1 Diabetes.
- Authors
van Lummel, Menno; Buis, David T. P.; Ringeling, Cherish; de Ru, Arnoud H.; Pool, Jos; Papadopoulos, George K.; van Veelen, Peter A.; Reijonen, Helena; Drijfhout, Jan W.; Roep, Bart O.
- Abstract
The heterozygous DQ2/8 (DQA1*05:01-DQB1*02:01/DQA1*03:01-DQB1*03:02) genotype confers the highest risk in type 1 diabetes (T1D), whereas the DQ6/8 (DQA1*02:01-DQB1*06:02/DQA1*03:01-DQB1*03:02) genotype is protective. The mechanism of dominant protection by DQ6 (DQB1*06:02) is unknown. We tested the hypothesis that DQ6 interferes with peptide binding to DQ8 by competition for islet epitope ("epitope stealing") by analysis of the islet ligandome presented by HLA-DQ6/8 and -DQ8/8 on dendritic cells pulsed with islet autoantigens preproinsulin (PPI), GAD65, and IA-2, followed by competition assays using a newly established "epitope-stealing" HLA/peptide-binding assay. HLA-DQ ligandome analysis revealed a distinct DQ6 peptide-binding motif compared with the susceptible DQ2/8 molecules. PPI and IA-2 peptides were identified from DQ6, of DQ6/8 heterozygous dendritic cells, but no DQ8 islet peptides were retrieved. Insulin B6-23, a highly immunogenic CD4 T-cell epitope in patients with T1D, bound to both DQ6 and DQ8. Yet, binding of InsB6-23 to DQ8 was prevented by DQ6. We obtained first functional evidence of a mechanism of dominant protection from disease, in which HLA molecules associated with protection bind islet epitopes in a different, competing, HLA-binding register, leading to "epitope stealing" and conceivably diverting the immune response from islet epitopes presented by disease-susceptible HLA molecules in the absence of protective HLA.
- Subjects
TYPE 1 diabetes; HLA-B27 antigen; INSULIN aspart; DENDRITIC cells; THEFT; ISLANDS of Langerhans
- Publication
Diabetes, 2019, Vol 68, Issue 4, p787
- ISSN
0012-1797
- Publication type
journal article
- DOI
10.2337/db18-0501