TGFB1 and endometriosis: In this study, we have demonstrated not only that the percentage of Treg cells in the peritoneal fluid of endometriosis patients higher than that in healthy women, which is consistent with results of previous published studies,23 but also that the augmentation of Treg cell percentage, especially that of TGF-β1+ Treg cells, occurs in parallel with endometriosis exacerbation.