Elevated interleukin-16 levels in the peritoneal fluid of women with endometriosis may be a mechanism for inflammatory reactions associated with endometriosis

OBJECTIVE: To investigate the role of interleukin (IL)-16 in peritoneal fluid in the pathogenesis of endometriosis. DESIGN: Comparative and laboratory study. SETTING: University of Tokyo Hospital. PATIENT(S): Peritoneal fluids (PFs) were collected from women without endometriosis (n = 34) and with endometriosis (stages I/II, n = 30; stages III/IV, n = 58). Peritoneal fluid mononuclear cells (PFMCs) were collected from six women. INTERVENTION(S): The PFs were collected; PFMCs were isolated and cultured with or without recombinant human (rh) IL-16. MAIN OUTCOME MEASURE(S): Concentrations of IL-16 in PFs were measured by enzyme-linked immunosorbent assay (ELISA). Concentrations of IL-6, tumor necrosis factor-alpha (TNF-alpha), and IL-1beta in culture media of PFMCs were determined by ELISA. RESULT(S): The IL-16 concentrations in the PF of women with advanced endometriosis (stages III/IV) (330 pg/mL, 231-501; median, interquartile range) were significantly higher (P=.0016) than those without endometriosis (229 pg/mL, 174-311). The PFMCs cultured with rhIL-16 released an increased amount of IL-6, TNF-alpha and IL-1beta, which was a 1.17-, 1.33-, and 1.54-fold increase, respectively, over that in the control culture. CONCLUSION(S): The present study indicates that IL-16 in PF may play a role in the pathogenesis of endometriosis by initiating or sustaining inflammatory responses in the peritoneal cavity.