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

The CD4+ T-cell receptor (TCR) recognizing CRM197-derived peptide–MHC class II complexes is a specialized immune receptor essential for the efficacy of conjugate vaccines (Avci et al., 2011; Pichichero, 2013). CRM197, a non-toxic variant of the diphtheria toxin, acts as a carrier protein that provides T-cell epitopes to enhance the immune response against poorly immunogenic antigens, such as bacterial polysaccharides (Giannini et al., 1984; Shinefield, 2010). Upon vaccination, antigen-presenting cells or B cells internalize the conjugate, process CRM197 into peptides, and present them via MHC class II molecules (Avci et al., 2011). The specific TCR on CD4+ T cells recognizes these peptide-MHC complexes, triggering T-cell activation and the release of helper cytokines like IL-4 and IL-21 (Pichichero, 2013). This T-cell help is crucial for B cells to undergo class switching and affinity maturation, resulting in the production of high-affinity IgG antibodies and the establishment of immunological memory (Avci et al., 2011). Because many individuals have pre-existing immunity to diphtheria toxin from childhood vaccinations, these TCRs are often part of a memory T-cell pool that can be rapidly mobilized (Shinefield, 2010). This interaction is the fundamental basis for the success of widely used vaccines against Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b (Pichichero, 2013). Understanding the diversity and affinity of these TCRs helps in designing more potent vaccines and predicting individual variations in vaccine responsiveness (Avci et al., 2011).

Other names

CRM197-specific T-cell receptorDiphtheria toxin-specific TCRCRM197-reactive TCRCRM197-specific CD4+ T-cell receptor

The TCR recognizes CRM197-derived peptides presented by MHC class II molecules on the surface of antigen-presenting cells or B cells, triggering T-cell activation and the provision of cognate help to B cells for high-affinity antibody production.