PDCD1 and endometriosis: Regarding Western blot results, ectopic endometriotic lesions showed a significant increase in PD-1 and PD-L1 expression compared with the controls and the eutopic endometrium from endometriosis samples (p < 0.01); eutopic endometrium from endometriosis also differed significantly from the controls, exhibiting greater PD-L1 expression (p < 0.01) [24].