| Autor: |
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. |
| Předmět: |
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| Zdroj: |
Diabetes; Apr2019, Vol. 68 Issue 4, p787-795, 9p, 3 Diagrams, 1 Chart, 1 Graph |
| Abstrakt: |
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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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