A LISTERIA-MONOCYTOGENES PENTAPEPTIDE IS PRESENTED TO CYTOLYTIC T-LYMPHOCYTES BY THE H2-M3 MHC CLASS IB MOLECULE

Polymorphism of MHC class Ia molecules severely constrains vaccine dev elopment against intracellular pathogens. Antigen presentation by MHC class Ib molecules, which are generally conserved between different in dividuals, may circumvent this obstacle. Herein, we use tandem mass sp ectrometry to identify a Listeria monocytogenes pentapeptide antigen t hat is presented to T lymphocytes by the H2-M3 MHC class Ib molecule. The peptide contains N-formyl methionine at the N terminus and exclusi vely hydrophobic amino acids. Mice of the H-2(d), H-2(b), and H-2(k) h aplotypes respond to this peptide upon infection with Listeria monocyt ogenes. Identification of antigens presented by MHC class Ib molecules is feasible and may provide opportunities for relatively unrestricted vaccine development.