Detection of peptide-MHC class II complexes on the surface of intact cells

The interaction of peptides with major histocompatibility complex proteins on the surface of cells is required for their recognition by T lymphocytes. Many studies characterizing the formation of peptide-MHC class II complexes have used either assays for T cell responses or for peptide binding to purified class II molecules. Recently, specific peptide-class II interactions have been demonstrated convincingly on the surface of intact cells. The effects of varying peptide and class II structure have been examined in order to identify structural requirements for binding to cell surface class II molecules and to examine the conformation adopted by immunogenic peptides when bound.