CD4+ T cell receptor recognizing CRM197 peptide–MHC class II complex (CRM197-specific TCR)

The CD4+ T cell receptor (TCR) recognizing CRM197 peptide–MHC class II complexes is a specialized immune receptor essential for the efficacy of conjugate vaccines. CRM197 is a non-toxic mutant of the diphtheria toxin (Gly52Glu) that acts as a carrier protein to convert T-cell independent polysaccharide antigens into T-cell dependent ones (Pecetta et al., 2016). When a conjugate vaccine is administered, antigen-presenting cells (APCs) internalize the complex and process CRM197 into peptides, which are then presented on Major Histocompatibility Complex (MHC) class II molecules (Broker et al., 2011). Specific TCRs on the surface of CD4+ T cells bind to these peptide-MHC II complexes, initiating a signaling cascade that leads to T-cell activation and the secretion of cytokines like IL-4 and IL-21. This T-cell activation is crucial for providing help to B cells, enabling them to undergo isotype switching and affinity maturation to produce high-titer, long-lasting antibodies against the target pathogen (Bottrel et al., 2004). Consequently, these TCRs are primary targets for monitoring vaccine immunogenicity and are central to the design of next-generation glycoconjugate vaccines.

Other names

CRM197-specific T-cell receptorTCR recognizing CRM197-MHCIIDiphtheria toxoid-specific T-cell receptorCRM197-specific CD4+ T cell receptor

CRM197-derived peptides are presented by MHC class II molecules to specific TCRs on CD4+ T cells, triggering T-cell activation and subsequent B-cell help for antibody production.