Modulation of neutrophil apoptosis by plasma and peritoneal fluid from patients with advanced endometriosis

BACKGROUND: The increased production of pro-inflammatory chemoattractant cytokines for neutrophils in endometriosis suggests that changes in the immune system play an important role in the pathophysiology of endometriosis. The effects of plasma and peritoneal fluid from patients with advanced endometriosis on the apoptosis of neutrophils were investigated. METHODS: Apoptotic changes of neutrophils were evaluated by morphological changes using Giemsa staining. Apoptosis was confirmed by DNA electrophoretic analysis. RESULTS: Compared with the plasma (n = 20) and peritoneal fluid (n = 5) of healthy controls, the addition of 10% plasma (n = 20) and peritoneal fluid (n = 10) from patients with endometriosis to an in-vitro culture of neutrophils from healthy subjects reduced the percentage of apoptotic cells from 65.3 +/- 6.6 to 27.2 +/- 4.6% (P < 0.001) and from 45.3 ± 4.8 to 10.5 ± 4.3% (P < 0.001) respectively. Neutralizing interleukin-8 antibody abrogated the delay of neutrophil apoptosis induced by peritoneal fluid, but not in the plasma of endometriosis patients. CONCLUSIONS: These findings show that interleukin-8 is one of the neutrophil survival factors in the peritoneal fluid of endometriosis patients and that an unidentified survival factor is also present in the plasma of patients with endometriosis.