High numbers of degranulated mast cells have been found in endometriotic lesions, mainly of deep infiltrating type, but not in non-affected areas from peritoneum or eutopic endometrium of patients, indicating that a reaction of hypersensitivity is strongly associated to endometriosis (80); released mediators include TNF-α, IL-8, MCP-1, RANTES, and stem cell factor (SCF) (81). This evidence concerns the gene CCL5 and endometriosis.