T cell receptor and costimulatory receptors (TCR and costimulatory receptors)

The T cell receptor (TCR) and costimulatory receptors represent a critical signaling nexus required for the initiation of an adaptive immune response against cancer (Chen & Flies, 2013). Dendritic cells, acting as professional antigen-presenting cells, capture tumor-associated antigens and present them as peptide-MHC complexes to the TCR, providing the primary activation signal (Banchereau & Steinman, 1998). Simultaneously, costimulatory molecules on the dendritic cell surface, such as CD80/86 or CD70, bind to receptors like CD28 or CD27 on the T cell to provide essential secondary signals for survival and effector function (Mellman et al., 2011). This coordinated engagement is the basis for several immunotherapeutic strategies, including dendritic cell vaccines like Sipuleucel-T and TCR-engineered T-cell therapies (Kantoff et al., 2010). By enhancing these interactions, therapies aim to overcome tumor-induced immune evasion and promote robust, antigen-specific anti-tumor activity. However, over-activation of these pathways can lead to significant safety concerns, such as cytokine release syndrome or systemic autoimmunity (June et al., 2018). The specificity of the TCR for tumor-associated antigens is a key determinant of the therapeutic index for these interventions. Overall, this target complex is central to the Cancer-Immunity Cycle, governing the transition from antigen recognition to effector T cell destruction of cancer cells.

Other names

T-cell activation complexSignal 1 and Signal 2 receptorsTCR-CD28 complexAntigen-specific T-cell receptorsImmunological synapse

Activation of T-cell mediated immunity through the dual engagement of the T-cell receptor by MHC-presented antigens and costimulatory receptors by their respective ligands.