Major histocompatibility complex class II presenting ovalbumin 323-339 peptide (MHC II-OVA323-339) (MHC II-OVA323-339)

The Major Histocompatibility Complex (MHC) class II presenting the ovalbumin 323-339 peptide (OVA323-339) is a fundamental model system used in immunology to study CD4+ T-cell responses (Scott et al., 1998, Immunity). This complex is formed when the 17-amino acid immunodominant epitope of chicken ovalbumin is processed and loaded onto MHC class II molecules, such as I-Ad or I-Ak in murine models (Robertson et al., 2000, J. Immunol.). Its primary biological role is the activation of antigen-specific T cells, particularly those expressing the OT-II transgenic T-cell receptor, which recognizes this specific peptide-MHC combination (Barnden et al., 1998, Immunol. Cell Biol.). In research settings, this target is pivotal for investigating the mechanisms of immune tolerance, the pathogenesis of allergic asthma, and the development of novel vaccine strategies (Lloyd et al., 2001, J. Exp. Med.). While not a direct therapeutic target in humans, it serves as a proxy for understanding how MHC-peptide complexes can be targeted by TCR-like antibodies or chimeric antigen receptor (CAR) T-cells in cancer and autoimmune therapies. Experimental agents interacting with this complex are used to modulate T-cell signaling, providing a platform for testing immunosuppressive or immunostimulatory drugs. The complex is also used in the form of fluorochrome-labeled tetramers to track and quantify antigen-specific T cells in vivo and in vitro. Its use has been instrumental in defining the two-signal model of T-cell activation, requiring both TCR engagement and co-stimulation.

Other names

I-Ad-OVA323-339I-Ak-OVA323-339MHC II-OVA peptide complexOvalbumin 323-339/MHC IIH2-Ab1-OVA323-339

The complex acts as a ligand for the T-cell receptor (TCR), triggering the formation of the immunological synapse and subsequent activation of the ZAP-70 and MAPK signaling pathways (Scott et al., 1998, Immunity).