Alpha-beta T-cell receptor (αβ TCR) (αβ TCR)

The alpha-beta T-cell receptor (αβ TCR) on CD4+ T cells is a heterodimeric surface protein responsible for recognizing specific antigenic peptides presented by Human Leukocyte Antigen (HLA) Class II molecules (UniProt: P01848). While CD4+ T cells are traditionally viewed as helper cells that coordinate immune responses through cytokine secretion, they can also exhibit direct cytotoxic activity against tumor cells when their TCRs recognize somatic mutations, known as neoantigens (PubMed: 32665311). This recognition is highly specific, as neoantigens are absent from the normal genome, making them ideal targets for precision immunotherapy (Science: 344(6215)). Therapeutic strategies targeting these complexes include adoptive TCR-engineered T-cell (TCR-T) therapy, where a patient's T cells are modified to express a high-affinity TCR specific to a tumor neoantigen-HLA II complex (NCI). Clinical applications have focused on targeting mutations in drivers like KRAS or shared antigens like MAGE-A3, aiming to overcome the limitations of HLA Class I-restricted therapies (PubMed: 24814342). However, challenges remain, including the heterogeneous expression of HLA Class II on solid tumors and the risk of cytokine-mediated toxicities (Nature Reviews Cancer: 21(7)). Monitoring HLA Class II expression and neoantigen load is essential for patient selection in these therapies (PubMed: 30249618).

Other names

T-cell receptorCD4+ T-cell receptorNeoantigen-specific TCRαβ TCR-CD3 complexAntigen-specific T-cell receptor

Engineered or endogenous TCRs bind to specific neoantigen peptides presented by HLA Class II molecules on the surface of target cells, triggering intracellular signaling via the CD3 complex and subsequent T-cell effector functions including cytokine release and direct lysis.