Oral Presentation The 13th International Congress of the Immunology of Diabetes Society 2013

Proinflammatory and regulatory autoreactive T cell responses to insulin are dependent upon HLA-DQ genotype (#50)

Maki Nakayama 1 , Liping Yu 1 , Marian Rewers 1 , Peter Gottlieb 1 , John Kappler 1 2 , Aaron Michels 1
  1. University of Colorado Denver, Aurora, CO, United States
  2. National Jewish Health, Denver, CO, United States

Class II major histocompatibility molecules confer disease risk and protection from type 1 diabetes (T1D) by modulating presentation of specific islet peptides to autoreactive CD4 T-cells in the thymus and periphery. Detecting insulin specific T-cell responses from the peripheral blood has been challenging due to low frequencies and incompletely defined epitopes. There is strong evidence from the nonobese diabetic mouse model of spontaneous autoimmune diabetes that insulin B chain amino acids 9-23 presented in low affinity register of binding by the murine class II molecule, I-Ag7, stimulates insulin specific CD4 T-cells. We investigated whether insulin B:9-23 peptides, designed to bind ‘diabetogenic’ HLA-DQ alleles (lacking β57 aspartic acid) in a similar low affinity register of binding, illicit T-cell responses in humans. We identified a mutated insulin B:9-23 peptide, substituting a single amino acid B22 arginine to glutamic acid, capable of inducing robust T cell responses in peripheral blood mononuclear cells greater than that of native B:9-23. New onset T1D patients (<3 weeks after diagnosis) having two non-β57Asp DQ alleles (i.e. DQ2 or DQ8) showed a proinflammatory response to the mutated insulin peptide with 8/17 subjects having >10 total IFN-γ ELISPOTs. Control subjects without diabetes responded with a regulatory phenotype producing IL10, rather than IFN-γ, dependent upon having a HLA-DQ allele with β57Asp (15/18 subjects with >20 IL-10 spots compared to 2/8 without a β57Asp DQ allele). Furthermore, unfractionated PBMCs from T1D subjects proliferated to the mutated insulin peptide to a greater degree than native peptide. T-cell receptor Vgene usage of CD4+CFSElo T-cells before and after proliferation revealed Vα skewing with four predominant Vα genes clustered together based upon similarity in CDR1 and CDR2 sequences. We conclude that a given HLA-DQ genotype leads to a polarization of T-cell response to insulin which may have important implications for antigen specific immunotherapy.