TNFRSF18 and neoplasm: Compared to other T cells, Tregs have an activated phenotype (ICOS, GARP, CD39, GITR, HLA-DR) [9, 11–13] and expand in situ through ICOS/ICOS-L interaction with tumor-infiltrating plasmacytoïd dendritic cells or tumor cells [11, 13–17].