T-cell receptor and major histocompatibility complex-peptide complex (TCR-pMHC)

The T-cell receptor and major histocompatibility complex-peptide (TCR-pMHC) complex is the fundamental structural unit of the adaptive immune system's antigen recognition process. It consists of a T-cell receptor (TCR) on the surface of a T lymphocyte binding to a specific peptide fragment presented by a Major Histocompatibility Complex (MHC) molecule on an antigen-presenting cell or target cell (Janeway et al., Immunobiology, 2001). This interaction is highly specific and triggers T-cell activation, proliferation, and effector functions, such as the killing of infected or malignant cells. In therapeutic contexts, the TCR-pMHC complex is targeted to redirect the immune system against specific diseases, particularly cancer, by engineering T cells (TCR-T therapy) or using bispecific molecules like ImmTACs that bridge T cells to specific pMHC targets (Nature Reviews Clinical Oncology, 2020). Because MHC molecules can present peptides derived from intracellular proteins, targeting this complex allows for the recognition of a much broader range of antigens than traditional antibody-based therapies which only target surface proteins. Notable approved therapies targeting this complex include Tebentafusp for uveal melanoma and Afamitresgene autoleucel for synovial sarcoma (FDA.gov, 2022, 2024). However, the high specificity required poses significant challenges, as cross-reactivity with similar self-peptides in healthy tissues can lead to severe or fatal off-target toxicities.

Other names

TCR-pMHC complexTCR-peptide-HLA complexMHC-peptide-TCR complexAntigen-specific TCR-MHC complex

Redirection of T-cell cytotoxicity and activation through the specific recognition of intracellularly-derived peptide fragments presented by MHC molecules.