PDCD1 and endometriosis: The CD8+/PD-1 : CD8+/PD-L1+ T cell ratio was also lower in the endometriosis group (6.36 ± 4.84, median 5.57, Min–Max 1.47–24.17) than in the healthy subjects (8.37 ± 4.01, median 7.42, Min–Max 3.58 ± 17.63) (p = 0.031).