AUTHOR=Kordelas Lambros , Claas Frans H. J. , Rebmann Vera TITLE=Editorial: “The Role of Immune Checkpoint Molecules in Solid and Hematopoietic Stem Cell Transplantation” JOURNAL=Frontiers in Immunology VOLUME=12 YEAR=2021 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.822558 DOI=10.3389/fimmu.2021.822558 ISSN=1664-3224