Microtiter plate immunoenzymometric assay for estrogen receptor

Area of Science:

• Oncology
• Biochemistry
• Immunology

Background:

• Estrogen receptor (ER) status is crucial for breast cancer prognosis and predicting response to endocrine therapy.
• Accurate ER quantification in tumors is essential for guiding treatment strategies.

Purpose of the Study:

• To develop and validate a novel immunoenzymometric assay (EIA96) for quantifying estrogen receptor (ER) in breast cancer cytosols.
• To assess the performance characteristics of the EIA96, including its detection limit and precision.
• To compare the EIA96 with established methods like radioligand assay (RLA) and Abbott ER-EIA.

Main Methods:

• Development of a two-step immunoenzymometric assay (EIA96) using two monoclonal antibodies against ER.
• Assay protocol involves incubation at 4°C for 16-18 hours and 3 hours, requiring 100 µL of cytosol.
• Performance evaluation included determination of detection limit, intra- and interassay coefficients of variation (CVs), and comparison with RLA and Abbott ER-EIA using breast adenocarcinoma tissue biopsies.

Main Results:

• The EIA96 demonstrated a low detection limit of 0.58 pmol/L.
• Intra- and interassay CVs for clinical specimens were consistently low (< or = 5%), indicating high precision.
• The EIA96 showed excellent agreement with the Abbott ER-EIA, though two samples yielded discrepant results compared to the RLA.

Conclusions:

• The developed EIA96 is a precise and reliable method for quantifying estrogen receptor levels in breast cancer cytosols.
• The assay exhibits strong concordance with existing methods, suggesting its utility in clinical settings.
• Further investigation may be warranted for discrepant results observed with the RLA.