Proinsulin peptide-HLA class I complex (PPI-HLA-I)

The proinsulin peptide-HLA class I complex is a molecular assembly consisting of a proinsulin-derived peptide (such as the C19-A3 epitope) bound to a Human Leukocyte Antigen (HLA) class I molecule. In Type 1 Diabetes (T1D), this complex is a primary target for autoreactive CD8+ T cells, which recognize it on the surface of pancreatic beta cells and mediate their destruction (NIH, 2012; 2020). Therapeutic strategies utilize this complex by loading proinsulin peptides onto ex vivo-generated tolerogenic dendritic cells (tolDCs). These tolDCs present the complex in a non-stimulatory environment—characterized by low costimulatory molecule expression and high anti-inflammatory cytokine production—to induce antigen-specific immune tolerance (Frontiers in Immunology, 2022). This process aims to suppress or delete pathogenic CD8+ T cells and induce regulatory T cells (Tregs), thereby preserving remaining beta-cell function and slowing disease progression in T1D patients (Lancet Diabetes Endocrinol, 2020).

Other names

Proinsulin-MHC class I complexPPI-HLA-I complexC19-A3-HLA-A2 complexProinsulin peptide-loaded HLA class IProinsulin-HLA-A*02:01 complexProinsulin-HLA-A*24:02 complex

Induction of antigen-specific immune tolerance through the presentation of autoantigenic peptides by tolerogenic dendritic cells, leading to the suppression, anergy, or deletion of autoreactive CD8+ T cells and the induction of regulatory T cells.