Human MHC class II–restricted T-cell receptor recognizing CRM197-derived peptides (CRM197-TCR)

The Human MHC class II–restricted T-cell receptor recognizing CRM197-derived peptides is a specialized immune receptor that mediates the recognition of the CRM197 carrier protein. CRM197 is a genetically detoxified mutant of diphtheria toxin (G52E) that is widely utilized in conjugate vaccines, such as those for Streptococcus pneumoniae and Haemophilus influenzae, to enhance the immunogenicity of polysaccharide antigens. This TCR specifically binds to CRM197-derived peptides presented by MHC class II molecules, most notably HLA-DR1, on the surface of professional antigen-presenting cells. Upon engagement, the TCR initiates a signaling cascade that activates CD4+ T helper cells, leading to the secretion of cytokines that facilitate B-cell maturation and antibody isotype switching. In the field of advanced immunotherapy, this TCR is being investigated as a tool for 'universal T-cell help.' By engineering T cells to express a CRM197-specific TCR, researchers aim to create a population of helper cells that can be selectively activated by CRM197-containing vaccines to boost anti-tumor immune responses. This approach is particularly relevant for overcoming the immunosuppressive environment of 'cold' tumors that lack sufficient endogenous T-cell help. The specificity and binding affinity of this TCR are critical parameters for both the efficacy of traditional conjugate vaccines and the development of novel TCR-engineered cellular therapies.

Other names

CRM197-specific T-cell receptorDiphtheria toxin-specific T-cell receptorCRM197-reactive TCRMHC II-restricted CRM197 TCR

The TCR recognizes and binds to specific peptides derived from the CRM197 protein (a non-toxic mutant of diphtheria toxin) when they are presented by human MHC class II molecules, such as HLA-DR1, on the surface of antigen-presenting cells. This binding event triggers the TCR-CD3 signaling complex, leading to the activation of CD4+ T helper cells. These activated T cells then proliferate and secrete cytokines (e.g., IL-2, IFN-gamma, and IL-4) that provide essential 'help' to B cells for antibody production and to CD8+ T cells for cytotoxic responses. In the context of conjugate vaccines, this mechanism converts T-independent polysaccharide antigens into T-dependent ones, ensuring long-term immunological memory.