ABSTRACT
Objective:To explore the expressions of programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) and clinicopathological characteristics in post-transplant lymphoproliferative disorder (PTLD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in children, with the aim of clarifying whether checkpoint inhibition of PD-1/PD-L1 inhibitors may serve as a therapy option.Methods:The clinical data of 13 cases of PTLD after allo-HSCT pathologically confirmed in Shenzhen Children′s Hospital from January 1, 2012 to December 30, 2019 were retrospectively analyzed.The detection was performed by immunohistochemical staining by MaxVision? method, Epstein-Barr virus(EBV) in situ hybridization and lymphoma gene rearrangement.The relationship between the expression of PD-1 and PD-L1 and the clinicopathological characteristics of PTLD were analyzed.Results:The expression of PD-1 was not correlated with gender, age, primary diseases, histopathological types, transplantation mode and the expression of EBV in situ hybridization (all P>0.05). The expression of PD-L1 was correlated with histopathological types ( P<0.05). Furthermore, the expression rate of PD-L1 on severe β-thalassemia was significantly higher than that of severe aplastic anemia [90.0%(9/10 cases) vs. 66.7%(2/3 cases)] and monomorphic PTLD was higher than that of polymorphic PTLD [100.0%(2/2 cases) vs. 83.3%(5/6 cases)]. Moreover, the positive PTLD in EBV was higher than the negative PTLD in EBV [90.9%(10/11 cases) vs. 50.0%(1/2 cases)]. The positive rates of PD-1 and PD-L1 in 13 cases with PTLD were 46.2%(6/13 cases) and 61.5%(8/13 cases) in tumor cells, 92.3% (12/13 cases) and 76.9% (10/13 cases) in microenvironmental cells, and 84.6%(11/13 cases) in EBV, respectively. Conclusions:PD-L1 has a higher positive rate in tumor cells with monomorphic PTLD; and routine staining for PD-1 and PD-L1 can be performed in all types of PTLD when standard immunotherapy and chemotherapy are ineffective.