While it is widely accepted that the menstrual cycle phase influences CD8 T cell counts and activation status in endometriosis-associated tissue, one of the included studies also found a clear correlation between the levels of several blood leukocytes and age, parity, previous use of oral contraceptives, smoking, and recent history of acute infection, but no other studies accounted for this (5, 47). This evidence concerns the gene CD8A and endometriosis.