Modulation of IL-6 production during the menstrual cycle in vivo and in vitro.

During the menstrual cycle (MC), premenopausal women experience changes in basal temperature and their physical condition and well-being. Premenopausal female patients with chronic inflammatory diseases demonstrate changes in disease activity during the MC. The study was initiated to explore reasons for these phenomena. The sex hormone-modulated lipopolysaccharide (LPS)-induced interleukin-6 (IL-6) secretion in a whole blood assay, serum IL-6 concentration, and serum sex hormone concentrations were studied throughout the MC in five healthy female subjects (median, 28 years; mean, 31.2+/-2.2 years, 26-38 years). Serum IL-6 concentration demonstrated a significant increase in the luteal phase of the MC and was elevated when serum dehydroepiandrosterone (DHEA) was low and vice versa. DHEA decreased LPS-induced IL-6 secretion at six of seven time points during the MC (DHEA, p = .047). In contrast, beta-estradiol and testosterone increased LPS-induced IL-6 secretion in six of seven time points during the MC (significant for testosterone, p = .005). The study demonstrates oscillation of serum IL-6 concentration during the MC and the marked MC-dependent modulation of IL-6 secretion by sex hormones. These mechanisms may be involved in the changes in the basal temperature, the general condition, and, in patients with chronic inflammatory diseases, of disease activity during the MC.