Increased Numbers of Activated Mast Cells in Endometriosis Lesions Positive for Corticotropin-Releasing Hormone and Urocortin

Problem: Mast cells are critical in allergic and inflammatory diseases such as interstitial cystitis, which is often clinically associated with or mistaken as endometriosis. Mast cells had previously been reported to be increased at sites of endometriosis, and tryptase may contribute to the fibrosis and inflammation characterizing endometriosis. Method of study: This is a pilot study of mast cell numbers and its activation in endometriosis biopsies (n = 10) by immunostaining for mast cell tryptase, corticotropin-releasing hormone (CRH) and urocortin (Ucn). Results: This is the first report that tryptase positive mast cells were not only increased (64–157 mast cells/mm2) in human endometriosis, but also highly activated (89%) in areas strongly stained positive for CRH/Ucn. Normal endometrium was weakly positive for both CRH/Ucn. Conclusion: High numbers of activated mast cells are present in endometriosis sites that were strongly positive for CRH/Ucn. CRH and Ucn may activate mast cells and contribute to the fibrosis and inflammation in endometriosis.