Quantitative Dot Blot (QDB) as a universal platform for absolute quantification of tissue biomarkers.

To circumvent the limitations associated with sandwich ELISA for tissue biomarker quantitation, Quantitative Dot Blot method (QDB) was proposed using antibodies clinically validated for immunohistochemistry (IHC), as this method requires only one primary antibody in the analysis. The protein levels of four breast cancer tissue biomarkers, including Estrogen Receptor (ER), Progesterone Receptor (PR), Ki67 and Her2, were absolutely quantitated successfully in 190 frozen breast tissue biopsies, and the results were further verified with provided IHC results. We propose QDB method as an alternative platform to Sandwich ELISA for absolute quantitation of tissue biomarkers with significantly reduced developing effort and time.