FULL-LENGTH CDNA OF RAT RT1.DMA AND RT1.DMB AND EXPRESSION OF RT1.DM GENES IN DENDRITIC AND LANGERHANS CELLS

MHC encoded DM heterodimers and classical MHC class II complexes meet in an endosomal/lysosomal compartment where DM heterodimers support pe ptide loading of MHC class II. Studies on peptide loading of rat class II and on peptide persistence in cells of the dendritic lineage promp ted us to establish full length cDNA clones coding for the subunits al pha and beta of rat DM molecules as well as a mAb directed against the luminal moiety of the beta subunit. Here we describe the establishmen t of the first full length cDNA clones of rat RT1.DMa and RT1.DMb. The mode of expression of RT1.DM at the transcript level in bone marrow c ulture-derived dendritic cells, in Langerhans cells and in a number of additional accessory cells is reported. The beta protein was identifi ed in detergent lysates of RT1.DM expressing cells by Western blot ana lysis using a newly established monoclonal antibody directed against t he luminal part of RT1.DM beta.