A study comparing leukocyte subsets in peripheral blood samples that were equally distributed across the menstrual cycle reported no differences in either CD8+ or CD8 T cell proportions between patients with endometriosis and healthy controls neither within the unadjusted model nor the model adjusted for age, smoking, oral contraception, parity, and history of an acute infection (CD8+: 16.4 ± 6.6 vs 16.7 ± 5.7, respectively; CD3+CD8+: 14.3 ± 5.3 vs 13.8 ± 5.7) (47). Here, CD8A is linked to endometriosis.