ObjectiveTo investigate the presence and modulation of growth-regulated α, a member of the chemokine family with neutrophil chemotactic activity, in the peritoneal fluid of women with or without endometriosis.MethodsPeritoneal fluid samples were obtained at laparoscopy from 63 women with endometriosis and 19 fertile women without endometriosis. Endometrial tissue was obtained from uteri after hysterectomy for reasons other than endometrial disease or from endometrial biopsies of reproductive-age women. Cellular RNA was extracted and northern blots were hybridized with an oligonucleotide probe complementary to a specific sequence of growth-regulated α messenger RNA. Growth-regulated α in peritoneal fluid and culture supernatant was quantified using enzyme-linked immunosorbent assay. Statistical analyses were performed using Kruskal-Wallis and Mann-Whitney tests.ResultsThe median (range) concentration of growth-regulated α in peritoneal fluid samples from 19 normal fertile women was 27 pg/mL (0-108), from 24 women with moderate endometriosis 34 pg/mL (8–150), and from seven with severe endometriosis was 73 pg/mL (10–221) (P= .04,P= .01, respectively). In the moderate and severe endometriosis groups, the levels of growth-regulated α were significantly higher in the peritoneal fluid of women with untreated endometriosis (73 pg/mL [10–221]) than in women with medically treated endometriosis (25 pg/mL [8–47]). In mesothelial and endometrial stromal cells in culture, growth-regulated α messenger RNA and protein were detectable constitutively; however, both interleukin-1α and tumor necrosis factor-α induced higher levels of growth-regulated α messenger RNA and protein in a dose- and time-dependent manner.ConclusionsGrowth-regulated α levels are elevated in the peritoneal fluid of women with moderate and severe endometriosis. This chemotactic factor, which acts via the interleukin-8 receptor, may play a role in the pathogenesis of endometriosis.