P02.01 T- and B-cell abundance are remarkably reduced in the immune microenvironment of post-transplant malignancies

Background Immunosuppressive medication is mandatory in the majority of solid organ transplant recipients to reduce risk allograft rejection. An increased develop cancer a negative side effect long-term immunosuppression and impaired immunosurveillance assumed as underlying mechanism. However, impact on tumor immune microenvironment (TME) poorly understood. In this study we aimed elucidate differences between infiltrates post-transplant malignancies non-immunosuppressed patients. Materials Methods 117 resected samples 80 (kidney, heart, lung liver) were included. Immunohistochemistry digital image analysis whole section slides was used quantify T- (CD3, CD8) B-cell (CD20) abundance TME 14 different types. These data calculate Immune-score tertiary lymphoid structures TME. Expression Human-Leucocyte-Antigen-I (HLA-I) programmed cell death ligand 1 (PD-L1) analyzed tissue microarrays. Clinical parameters included statistical analyses. Results The reflected by remarkably reduced infiltrate central region (CT) surrounding (invasive margin, IM) areas. T decreased IM CT skin (814 vs. 1440 CD3 + cells/mm 2 , p < 0.01) non-skin tumors (479 781 0.01), when compared controls. more pronounced than larger comparing CD8 cells. integrating results from also recipients. Similar observed for cells, B density lower Decreased expression HLA-I common whereas fraction with PD-L1 higher Conclusions Our demonstrates that show low supports hypothesis anti-tumor response an important mechanism Optimized immunosuppressive protocols may be able incidence therapies need consider distinct malignancies. Disclosure Information S. Schran: None. R. Datta: O. Persa: C. Aguilar: M. Thelen: J. Lehmann: Garcia-Marquez: K. Wennhold: A. Quaas: Bruns: Mauch: H. Löser: D. Stippel: Schlößer: