Apoptosis Induction of Mouse Splenic Cells by Exposure to High-Level 17β-Estradiol and Endocrine Disrupting Chemicals

Abstract

The immunotoxicological effect of 17β-estradiol and other estrogenic compounds was determined with respect to lymphocyte apoptosis. High concentrations (10^-6-10^-5 M) of 17β-estradiol inhibited lymphocyte proliferation. DNA fragmentation was observed by agarose gel electrophoresis when lymphocytes were exposed to 17β-estradiol, confirming the occurrence of apoptosis. After exposure to 17β-estradiol, the lymphocytes underwent apoptosis within 12 hr of culture through three sequential alterations of membrane structure, as judged by the results of staining with three kinds of dyes, namely annexin V, which binds on the surface of the cell membrane, and propidium iodide and trypan blue, which cross the cell membrane. Diethylstilbestrol killed more cells whereas bisphenol A, a weak estrogen, induced apoptosis in fewer cells. These results suggest that 17β-estradiol and other estrogenic compounds induce lymphocyte apoptosis.