Ovalbumin peptide (323-339) bound to Major Histocompatibility Complex class II I-A subregion (I-Ab) (OVA323-339/I-Ab)

The OVA323–339 peptide bound to the I-Ab MHC class II molecule is a cornerstone model system in cellular immunology, particularly for studying CD4+ T-cell responses in C57BL/6 mice (Murphy et al., Janeway's Immunobiology). The peptide, derived from chicken egg ovalbumin (residues 323-339: ISQAVHAAHAEINEAGR), is processed and presented by dendritic cells via the I-Ab allele of the Major Histocompatibility Complex (MHC) class II (Robertson et al., 2000, J. Immunol.). This specific peptide-MHC (pMHC) complex is recognized with high specificity by the T-cell receptor (TCR) of OT-II transgenic mice, making it an invaluable tool for investigating antigen recognition, T-cell priming, and the mechanisms of immune tolerance (Barnden et al., 1998, Immunol. Cell Biol.). In therapeutic research, this complex serves as a target for developing novel immunotherapies, such as TCR-like antibodies and tolerogenic vaccines designed to modulate immune responses (Pugholm et al., 2015, Expert Rev. Vaccines). Its role is primarily as a benchmark for understanding how dendritic cells orchestrate the transition from innate to adaptive immunity.

Other names

OVA(323-339)-I-Ab complexOvalbumin 323-339 peptide-MHC II complexISQAVHAAHAEINEAGR/I-AbOVA-MHC II complexpMHCII (OVA323-339)

The complex acts as a ligand for the T-cell receptor (TCR) on CD4+ T cells, specifically the OT-II TCR, triggering a signaling cascade that leads to T-cell proliferation, cytokine production, or the induction of regulatory T cells depending on the co-stimulatory context (Barnden et al., 1998, Immunol. Cell Biol.).