Platelets and other inhibitory cytokines, IL-6, IL-16, IL-17, IL-1β, IL-10, and TGF-β, are found in the peritoneal fluid in patients with endometriosis and function to prevent the NK cells from degranulation and producing interferon (IFN)-γ, impairing the NK cell function. This evidence concerns the gene IFNG and endometriosis.