T cell receptor specific for Influenza Hemagglutinin peptide-MHC class II complex (HA-specific TCR)

The T cell receptor (TCR) specific for Influenza Hemagglutinin (HA) peptide-MHC class II complexes is a specialized protein complex found on the surface of CD4+ T helper cells. Its primary biological function is the recognition of specific HA-derived peptides, such as the immunodominant HA 306-318 epitope, when presented by Major Histocompatibility Complex (MHC) class II molecules (e.g., HLA-DR4) on antigen-presenting cells (PMID: 1563488, 7514392). This recognition event is fundamental to the adaptive immune response, triggering T cell proliferation, cytokine secretion, and the provision of help to B cells for antibody production (UniProt P03437). In clinical research, this TCR serves as a model for understanding T cell tolerance and memory, and it is a target for developing TCR-engineered T cell (TCR-T) therapies aimed at treating severe viral infections or as a proof-of-concept in immunotherapy (PMID: 28250417). While targeting this receptor can enhance viral clearance, it also poses risks such as cytokine release syndrome or potential cross-reactivity with self-antigens, which could lead to autoimmune complications (PMID: 10508254).

Other names

Hemagglutinin-specific T-cell receptorHA-TCRTCR recognizing HA306-318:HLA-DR4Influenza HA-specific CD4+ TCR6.5 TCR (mouse model)TS1 TCR (mouse model)

The TCR specifically binds to the HA peptide-MHC class II complex on antigen-presenting cells, which triggers the phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMs) on the associated CD3 chains. This initiates a downstream signaling cascade involving ZAP-70 and Lck, leading to the activation of transcription factors like NFAT, NF-κB, and AP-1, which drive T cell proliferation, differentiation into helper subsets, and cytokine production (PMID: 1563488, 28250417).