ENTPD1 and neoplasm: To further compare the phenotypic molecular characteristics of CD4+CCR8+ Tregs in peripheral circulation and that infiltrated in tumor tissues, flow cytometry was used to detect the proportions of PD-1+, CTLA4+, CD39+ cell subsets and the MFI values of Foxp3, PD-1, CTLA4 and CD39 on CD4+CCR8− Tregs and CD4+CCR8+ Tregs from HC-PBL group (n = 10), OC-PBL group (n = 16) and OC-TIL group (n = 12) (Fig. 3A–C).