Fig. 3

Histopathological analysis by immunohistochemical staining. To elucidate the pathogenesis of ATL after renal transplantation, we performed histopathological analysis using immunohistochemical staining [35]. In Case 1, a high numbers of PD-1-positive TIL cells (average 20.8/HPF) were noted. Microenvironmental PD-L1 expression was also positive (50/HPF). However, Fox P3, HLA class I, HLA class II, and neoplastic PD-L1 expression was not detected. In Case 2, low numbers of PD-1-positive TIL cells (average 0.8/HPF) were observed. Fox P3, HLA class I, HLA class II, neoplastic PD-L1, and microenvironmental PD-L1 were not expressed