T-cell receptor – Human Leukocyte Antigen – peptide complex (TCR-pHLA)

The T-cell receptor – Human Leukocyte Antigen – peptide complex (TCR-pHLA) is the fundamental molecular assembly responsible for adaptive immune recognition (1.2.2, 1.5.1). It consists of a heterodimeric T-cell receptor (TCR) that specifically binds to a peptide antigen presented within the groove of a Human Leukocyte Antigen (HLA) molecule on the surface of an antigen-presenting or target cell (1.2.1, 1.4.1). This interaction allows the immune system to survey the intracellular proteome, identifying fragments of viral, bacterial, or mutated proteins that indicate infection or malignancy (1.3.3, 1.4.4). In modern immunotherapy, this complex serves as a critical target for TCR-engineered T-cell (TCR-T) therapies and bispecific T-cell engagers, such as tebentafusp, which redirect cytotoxic T cells to eliminate diseased cells (1.1.1, 1.2.2). A major challenge in targeting these complexes is the risk of off-target cross-reactivity, where a therapeutic TCR may recognize structurally similar self-peptides on healthy tissues, potentially leading to severe autoimmune-like toxicities (1.1.2, 1.1.3). Precision in target selection, including specific HLA restriction and peptide-level specificity, is therefore essential for the safety and efficacy of drugs hitting this target (1.3.1, 1.4.2).

Other names

TCR-pMHC complexT-cell receptor – MHC – peptide complexTrimolecular complexPeptide-HLA-TCR complexpMHC-TCR complex

Drugs targeting this complex typically utilize engineered T-cell receptors (TCRs) or TCR-mimic antibodies to recognize specific peptide-HLA combinations on target cells, subsequently triggering T-cell mediated cytotoxicity through direct cell-cell interaction or bispecific recruitment (1.1.1, 1.2.2, 1.3.3).