C19-A3-specific CD4+ T-cell receptor (C19-A3 TCR)

The C19-A3-specific CD4+ T-cell receptor is a specialized immune receptor found on T-helper cells that recognizes a specific epitope of the proinsulin protein. This epitope, designated C19-A3, is a naturally processed peptide spanning the junction between the C-peptide and the A-chain of proinsulin (residues 75-92), and it is presented by the high-risk human leukocyte antigen (HLA) allele HLA-DR4, specifically DRB1*04:01. In patients with type 1 diabetes, these TCRs are often found on autoreactive T cells that contribute to the destruction of insulin-producing pancreatic beta cells. Therapeutic strategies targeting these receptors aim to induce immune tolerance rather than activation. This is achieved through antigen-specific immunotherapies (ASI), such as the intradermal administration of the C19-A3 peptide alone or conjugated to gold nanoparticles (C19-A3-GNP), which promote the expansion of regulatory T cells (Tregs) and the suppression of pathogenic autoimmune responses. Monitoring the activity of these TCR-bearing cells and the levels of biomarkers like C-peptide is crucial for evaluating the efficacy of such disease-modifying treatments in preserving beta-cell function.

Other names

Proinsulin 75-92-specific T-cell receptorHLA-DR4-restricted proinsulin TCRPI C19-A3 TCRProinsulin C19-A3-specific CD4+ T-cell receptor

The target is engaged by peptide-MHC complexes (specifically C19-A3 peptide presented by HLA-DR4) to modulate the activity of autoreactive CD4+ T cells. In the context of antigen-specific immunotherapy for type 1 diabetes, the goal is to induce immune tolerance through the expansion of regulatory T cells (Tregs), induction of anergy, or deletion of pathogenic T cells, thereby preventing the autoimmune destruction of pancreatic beta cells.