Interactions of the human class II major histocompatibility complex protein HLA-DR4 with a peptide ligand...

The interactions of empty recombinant major histocompatibility complex (MHC) class II molecules (DRA1*0101/DRB1*0401) with a known peptide ligand [the HA(307-319) fragment of influenza virus hemagglutinin] were studied by capillary electrophoresis. Using an alkaline buffer system with the addition of non-ionic or zwitterionic detergent and high sensitivity laser-induced fluorescence detection, both slowly and rapidly equilibrating binding could be demonstrated. This was accomplished using a pre-equilibration approach as well as migration shift experiments where receptor molecules were added to the electrophoresis buffer. This system may be useful for the study of both peptide binding to MHC molecules and screening for inhibition or amplification of binding by other ligands as well as for the study of the interactions of T-cell receptors with MHC-peptide complexes.