Chemokine bioactivity of RANTES in endometriotic and normal endometrial stromal cells and peritoneal fluid

Endometriotic lesions secrete chemokines that recruit immune cells into the peritoneal cavity. The accumulation of these immune cells, especially activated macrophages and T lymphocytes, is thought to mediate inflammatory symptoms associated with endometriosis. Previous studies have demonstrated that RANTES (regulated on activation, normal T cell expressed and secreted) is synthesized by endometriotic stromal cells and circulates in peritoneal fluid, commensurate with the stage of endometriosis. In the current studies, we used the human monocytic cell line, U937, to assay chemotactic activity in cell culture conditioned media and peritoneal fluid from patients with endometriosis and normal controls. We demonstrated expression of the human RANTES receptors CCR-1 and CCR-5 in U937 cells and peritoneal macrophages. Over a range of 0-1000 pg/ml recombinant human RANTES had a direct, linear effect on monocyte migration. Conditioned media and peritoneal fluid induced dose-dependent effects on monocyte migration that were correlated with concentrations of immunoreactive RANTES (as measured by enzyme-linked immunosorbent assay) and the severity of endometriosis. Heat denaturation of the RANTES protein or addition of anti-human RANTES antibodies neutralized the chemoattractant effects of conditioned media and peritoneal fluid. RANTES stimulation of monocyte recruitment may be an important pathogenetic target for the treatment of infertility and pain associated with endometriosis.