Journal Article Hematopoietic stem cell transplantation Research Support, Non-U.S. Gov't 4-1BB 4-1BB Ligand 9007-49-2 Adaptive immunity Case Reports DNA 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 Newborn screening RFXANK protein, human RFXAP protein, human Receptors, Antigen, T-Cell Recurrent lymphoproliferation Research Support, N.I.H., Extramural Secondary malignancy Severe combined immunodeficiency T-cell receptor excision circles (TRECs)