Gliadin-Specific CD8 + T Cell Responses Restricted by HLA Class I A0101 and B0801 Molecules in Celiac Disease Patients

• Published in: The Journal of immunology (1950) 2017-03, Vol.198 (5), p.1838-1845
• Main Authors: Picascia, Stefania, Sidney, John, Camarca, Alessandra, Mazzarella, Giuseppe, Giardullo, Nicola, Greco, Luigi, Auricchio, Renata, Auricchio, Salvatore, Troncone, Riccardo, Sette, Alessandro, Gianfrani, Carmen
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Algorithms; Alleles; Assaying; Autoimmune diseases; Blood cells; Carrier Proteins - immunology; Carrier Proteins - physiology; CD8 antigen; CD8-Positive T-Lymphocytes - immunology; Celiac disease; Celiac Disease - genetics; Celiac Disease - immunology; Celiac Disease - physiopathology; Child; Child, Preschool; Computational Biology; Enzyme-linked immunosorbent assay; Enzyme-Linked Immunospot Assay; Epitopes; Epitopes, T-Lymphocyte - immunology; Female; Genes, MHC Class I; Genome-wide association studies; Genomes; Gliadin; Gliadin - immunology; Gluten; Glutens - immunology; Haplotypes; Histocompatibility antigen HLA; HLA-A1 Antigen - genetics; HLA-A1 Antigen - immunology; HLA-A1 Antigen - metabolism; HLA-B8 Antigen - genetics; HLA-B8 Antigen - immunology; HLA-B8 Antigen - metabolism; Humans; Interferon; Interferon-gamma - genetics; Interferon-gamma - immunology; Linkage disequilibrium; Lymphocytes; Lymphocytes T; Male; Middle Aged; Peptides; Peptides - immunology; Peptides - metabolism; Peripheral blood; Proteins; Young Adult; γ-Interferon
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.1601208

Initial studies associated the HLA class I A*01 and B*08 alleles with celiac disease (CD) susceptibility. Subsequent analyses showed a primary association with HLA class II alleles encoding for the HLA DQ2.5 molecule. Because of the strong linkage disequilibrium of A*01 and B*08 alleles with the DR3-DQ2.5 haplotype and a recent genome-wide association study indicating that B*08 and B*39 are predisposing genes, the etiologic role of HLA class I in CD pathogenesis needs to be addressed. We screened gliadin proteins (2α-, 2ω-, and 2γ-gliadin) using bioinformatic algorithms for the presence of peptides predicted to bind A*0101 and B*0801 molecules. The top 1% scoring 9- and 10-mer peptides ( = 97, total) were synthesized and tested in binding assays using purified A*0101 and B*0801 molecules. Twenty of ninety-seven peptides bound B*0801 and only 3 of 97 bound A*0101 with high affinity (IC < 500 nM). These 23 gliadin peptides were next assayed by IFN-γ ELISPOT for recognition in peripheral blood cells of CD patients and healthy controls carrying the A*0101 and/or B*0801 genes and in A*0101/B*0801 CD patients. Ten of the twenty-three peptides assayed recalled IFN-γ responses mediated by CD8 T cells in A*0101/B*0801 patients with CD. Two peptides were restricted by A*0101, and eight were restricted by B*0801. Of note, 50% (5/10) of CD8 T cell epitopes mapped within the γ-gliadins. Our results highlight the value of predicted binding to HLA molecules for identifying gliadin epitopes and demonstrate that HLA class I molecules restrict the anti-gluten T cell response in CD patients.