Scientific Background | Ovalbumin 323-339 is one of the most widely used model antigens in immunology. Because chicken ovalbumin is foreign to mice but otherwise inert, this fragment provides a defined CD4+ T-cell epitope that can be introduced into almost any experimental system, and two transgenic T-cell receptor lines, OT-II and DO11.10, were raised specifically against it. That pairing of a defined peptide with a matched monoclonal T-cell population is what makes the system so widely adopted for tracking antigen-specific responses in vivo. The peptide is presented on MHC class II, and work on its interaction with I-A(d) showed that it can occupy the binding groove in more than one register, with the registers being functionally distinct rather than equivalent. That detail matters when interpreting responses: different T-cell clones raised against the same peptide may be reading different registers of it. Corresponding MHC class II tetramers are available commercially, so antigen-specific cells can be enumerated directly. |
