Detection of interleukin-6 in human follicular fluid

Abstract

To determine if interleukin-6 (IL-6) is a normal constituent of human follicular fluid (FF) after ovarian hyperstimulation and to assess whether IL-6 levels differ in conditions associated with immunological causes of infertility. After ovarian hyperstimulation for an in vitro fertilization (IVF) treatment cycle, FF samples were obtained at the time of oocyte retrieval. Referral center at a tertiary care hospital. Thirty women referred for IVF, including 10 patients with significant titers (greater than 40%) of antisperm antibodies and 10 with pelvic endometriosis. Ten patients with tubal infertility without antisperm antibodies or endometriosis served as controls. Analysis of FF levels for IL-6 using both bioassay and immunoassay. Bioactive (range 0.32 to 32.2 U/mL) and immunoreactive (range 0.34 to 13.6 ng/mL) IL-6 levels were detected in FF of all subjects after ovarian hyperstimulation. Follicular fluid IL-6 levels were substantially higher (3 to 30-fold) than that reported in serum. There was no difference in the mean concentrations of IL-6 levels between patients with antisperm antibodies, endometriosis, or tubal infertility. Bioactive and immunoreactive IL-6 are present in human FF after ovarian hyperstimulation, supporting a potential autocrine or paracrine role within the follicular microenvironment.