Journal Article Hematopoietic stem cell transplantation 4-1BB 4-1BB Ligand Adaptive immunity Case Reports DNA-Binding Proteins Enteropathy Epstein Barr virus HLA-DR HLA-DR Antigens HSCT Inborn errors of immunity Intestinal epithelial cells Invariant chain MHC class II deficiency Mixed Chimerism Mucosal immunity RFXANK protein, human RFXAP protein, human Recurrent lymphoproliferation Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Secondary malignancy TNFRSF9 protein, human Transcription Factors Tumor Necrosis Factor Receptor Superfamily, Member 9