AUTHOR=Freund Christian , Höfer Thomas TITLE=A Missing Switch in Peptide Exchange for MHC Class II Molecules JOURNAL=Frontiers in Immunology VOLUME=10 YEAR=2019 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2019.02513 DOI=10.3389/fimmu.2019.02513 ISSN=1664-3224