A simple and rapid method using polyethylenimine-treated filters for assay of solubilized LH/hCG receptors

Filtration through polyethylenimine (PEI)-treated membrane filters efficiently separates free radiolabeled human (h) LH or hCG from solubilized receptor-hormone complexes. Solubilized LH/hCG receptors of bovine, porcine, and rat origin are suitable for measurement by this method. Specific binding assayed by the PEI-filter technique was 106-138% of specific binding assayed by double polyethylene glycol precipitation, demonstrating that the method gave quantitative recovery of bound hormone. Nonspecific binding was consistently lower with PEI-treated filters. Intra- and interassay variability for the two different methods was similar. These results indicate that filtration through PEI-treated membrane filters is a simple and rapid method for assay of solubilized LH/hCG receptors.