Altered interleukin-6 production by peritoneal leukocytes from patients with endometriosis

To investigate the ability of peritoneal leukocytes to produce interleukin-6 (IL-6) in vitro and to determine whether IL-6 is present in the peritoneal fluid (PF) in vivo.

Peritoneal leukocytes were assessed for spontaneous versus stimulated IL-6 production. Interleukin-6 in the PF was also quantitated.

Leukocytes were recovered from PF obtained at the time of diagnostic laparoscopy for pain and infertility or from women undergoing bilateral tubal ligation.

The study population included a total of 24 women. Experimental groups consisted of women undergoing tubal ligations (n = 6), patients with postinflammatory pelvic adhesions unrelated to endometriosis (n = 6), and women with minimal to mild endometriosis (n = 6), or moderate to severe disease (n = 6).

Peritoneal leukocytes from normal control women and patients with severe endometriosis spontaneously produced low levels of IL-6. In contrast, cells from women with mild disease or adhesions spontaneously released twofold to fourfold higher levels of this cytokine. Peritoneal leukocytes from patients with both mild and severe endometriosis were refractory to additional cytokine release directly in response to stimulation with endotoxin. Bioactive IL-6 was present in the PF of all patient groups, whereas immunoreactive IL-6 was not detected in this fluid.

These data demonstrate that IL-6 was present in the PF of all patient groups. However, the ability of peritoneal leukocytes to produce IL-6 in vitro differed according to stage of disease. We hypothesize that altered leukocyte IL-6 production in vivo may contribute to the pathophysiology of endometriosis.