B3GAT1 and primitive neuroectodermal tumor: Intercellular transfer of CD57 from tumor cells to T cells may have to be considered in the interpretation of phenotyping results for TILs from CD57+ tumor entities such as brain tumors [6,24-26] and neuroectodermal tumors (including neuroblastoma, Ewing's sarcoma, and melanoma [15,16,27,28]), at least in case of in situ analyses such as immunohistochemical analyses.