The B chain of mammalian insulins contains appropriately spaced amino acids that predict recognition by T cells. However, all T cell clones from an HLA-DR1, Dw6 diabetic donor recognize epitopes associated with the A chain, and the B chain was found to inhibit these responses. Effective intramolecular competition at the level of the APC, not a direct effect on the T cell, is responsible for the inhibition. Insulin B chain contains two clusters of amino acid homology with the TCR beta chain and B chain peptides lacking these clusters do not compete for antigen presentation. A hole in the repertoire for T cells that recognize this portion of the insulin molecule may arise in the thymus by deletion of T cells that recognize similar peptides.
Insulin B chain functions as an effective competitor of antigen presentation via peptide homologies present in the thymus.
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G G Miller, J F Hoy, J W Thomas; Insulin B chain functions as an effective competitor of antigen presentation via peptide homologies present in the thymus.. J Exp Med 1 June 1989; 169 (6): 2251–2256. doi: https://doi.org/10.1084/jem.169.6.2251
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