CD27 and breast cancer: Moreover, PD-L1 levels in Vδ1 T cells were increased post-surgery (p < 0.001, Fig. 2g), which may contribute to the post-operative immunosuppressive status.13 Furthermore, the expression levels of regulatory immune cell markers (CD27, CD25, CD39, CTLA-4, CD122 and FoxP3) between CD73+ and CD73-Vδ1 T cells in BC tissue were also compared, and the results indicated CD73+ Vδ1 T cells expressed higher levels of CD27, CD122, CTLA-4 and FoxP3 (Supplementary Fig. S3).