Fig. 1.

Major microenvironment influencing factors. A schematic overview of the 4 major factors influencing the tumor microenvironment in post-transplant lymphoproliferative disorders. The Epstein-Barr virus has multiple para- and autocrine effects; chronic antigen stimulation leads to T-cell exhaustion; iatrogenic immunosuppression causes T-cell depletion and possible interactions between host derived and (co-)transplanted donor immune cells need to be further investigated