Effect of 17β-estradiol on tumor necrosis factor-α-induced cytotoxicity in the human peripheral T lymphocytes

We determined the effect of 17-estradiol on tumor necrosis factor (TNF-)-induced cytotoxicity in human peripheral T lymphocytes (T cells) using lactate dehydrogenase assay. Treatment with 17-estradiol (1–100 nM) for 24 h showed dose-dependent reduction of TNFinduced cytotoxicity in T cells. To further evaluate the mechanism of 17-estradiol on TNF--induced cytotoxicity in T cells, we identified estrogen receptor (ER) protein in T cells using immunocytochemistry and used the pure ER antagonist ICI 172,780. ER immunoreactivity was clearly observed in T cells. ER immunoreactivity was also detected in some T cells. ICI 172,780 (10 7 M) alone did not affect cytotoxicity in T cells, however, ICI 172,780 (10 7 M) completely abolished