A New Recombinant Cell Bioassay for Ultrasensitive Determination of Serum Estrogenic Bioactivity in Children

The evaluation of estrogenic status is necessary for many physiological and pathological conditions in pediatric as well as adult endocrinology. Because current immunoassays exclusively measure E2—and with a sensitivity that is insufficient for prepubertal children—we developed a new recombinant cell bioassay for ultrasensitive determination of serum estrogenic bioactivity. This assay is based on human uterine cervix carcinoma cells, HeLa cells, that do not naturally express E2 receptor. These cells were transfected with plasmids encoding the human ERα or β, along with an estrogen-responsive promoter fused to the luciferase gene, and called HELNα and HELNβ for HeLa estrogen-responsive element luciferase neomycin α and β. HELNα and HELNβ are able to respond to estrogens and various compounds having estrogenic activity but, because of the importance of ERα in the reproductive function, we chose to work with the HELNα cell line. The luciferase activity we obtained was compared with an E2 standard curve speci...