Immunization with an insulin peptide-MHC complex to prevent type 1 diabetes of NOD mice

Background Mutating the insulin B: 9-23 peptide prevents diabetes in NOD mice. Thus, the trimolecular complex of I-A(g7)-insulin B: 9-23 peptide-TCR may be essential for the development of spontaneous diabetes. Pathogenic T cells recognize the B: 9-23 peptide presented by I-A(g7) in what is termed register 3, with the B22 basic amino acid (arginine) of the peptide bound in pocket 9 of I-A(g7). Our hypothesis is that immunization with an insulin B: 12-22 peptide linked to I-A(g7) in register 3 (I-A(g7)-B:RE#3 complex) can induce specific antibodies to the complex, block pathogenic TCRs, and thus prevent diabetes. Methods We immunized young NOD mice with recombinant I-A(g7)-B:RE#3 protein, in which two amino acids of the peptide were mutated to fix the peptide in register 3, and investigated the induced antibodies targeted to the peptide in register 3. Results Specific antibodies targeting I-A(g7)-B: RE#3 but not I-A(g7)-HEL were identified in the sera of I-A(g7)-B: RE#3 immunized mice. The sera inhibited B: 9-23-induced T-cell responses in vitro. I-A(g7)-B:RE#3 immunization delayed progression to diabetes (versus PBS, p = 0.0005), while immunization with I-A(g7)-HEL control complex did not. Conclusions Immunization with I-A(g7)-B:RE#3 complex significantly delays the development of insulin autoantibodies and the onset of diabetes in NOD mice, which is associated with the induction of I-A(g7)-B:RE#3 antibodies. Copyright (C) 2011 John Wiley & Sons, Ltd.