OT-I T cell receptor (OT-I TCR) (OT-I TCR)

The OT-I T cell receptor (TCR) is a transgenic antigen receptor that specifically recognizes the SIINFEKL peptide (residues 257–264) of chicken ovalbumin presented by the murine MHC class I molecule H-2Kb (Hogquist et al., 1994, Cell). It is a heterodimer typically composed of Vα2 and Vβ5 chains, serving as a primary model for studying CD8+ T cell biology, including activation, clonal expansion, and memory formation (UniProt). In the context of immunotherapy, the OT-I system is extensively used to model TCR-engineered T cell (TCR-T) responses against tumors and to investigate the mechanisms of immune evasion (Restifo et al., 2012, Nature Reviews Immunology). The receptor's high affinity for its cognate peptide-MHC (pMHC) complex allows for precise tracking of T cell responses using H-2Kb-SIINFEKL tetramers (PubMed). While primarily a research tool, it provides the foundational framework for developing human TCR-based therapeutics targeting neoantigens or viral proteins. Safety concerns associated with such TCR-based interventions include potential cross-reactivity with self-antigens and the risk of cytokine release syndrome (CRS) upon robust T cell activation. This model remains indispensable for evaluating the potency and specificity of novel immunomodulatory drugs and vaccines.

Other names

OT-1 T cell receptorOvalbumin-specific T cell receptorVα2/Vβ5 T cell receptorH-2Kb-SIINFEKL-specific TCR

The OT-I TCR binds specifically to the SIINFEKL peptide presented by the H-2Kb MHC class I molecule, triggering a signaling cascade through the CD3 complex that leads to T cell proliferation, cytokine production, and targeted lysis of antigen-presenting cells (Hogquist et al., 1994).