Estradiol (E2) is a naturally occurring steroidal sex hormone that is essential for female fertility and maintenance of secondary sexual characteristics. Estradiol upregulates IL-6 expression through estrogen receptor beta (ERβ).

ERα (mouse):22-28 nM, ERα (human):22-28 nM, ERα:22-28 nM

Estradiol is dissolved in 0.01% ethanol. Briefly, B9 cells (5×103/well of a 96-well plate) are cultured with a series of dilutions of the supernatants in a final volume of 100 mL of RPMI 1640, supplemented with 5×10-5mol/Lof 2-mercaptoethanol, 10% FBS, 100 U/mL penicillin, and 100 μg/mL streptomycin in flat-bottom microtiter plates. After 42 h, 0.5 μCi of [3H]thymidine is added. 6 h later, the cells are harvested and the radioactivity incorporated is determined. IL-6 is quantitated from a standard curve set up with known amounts of recombinant human or mouse IL-6. The anti-IL-6 monoclonal antibody completely inhibited the ability of the B9 cells to proliferate in response to recombinant mouse IL-6. In addition, we determined that B9 cells do not proliferate in response to IL-I or TNF, and that antibodies to these two cytokines did not affect the cell proliferation in response to IL-6. Further, it is established that neither Estradiol (17β-estradiol), nor the 0.01% ethanol used as vehicle in these experiments, has any effect on the bioassay.