Combined immunoprecipitation and agglutination for the detection of the heterodimeric molecule: Human chorionic gonadotropin as a study model

Double-particle reversed passive hemagglutination (RPHA) was performed for the detection of an intact heterodimeric form of human chorionic gonadotrop in (intact hCG) composed in Profasi(R) hCG (P-hCG). This technique relied o n two mixed types of human O RBC, which were individually coated with two d istinct monoclonal antibodies that recognized alpha or beta subunit of hCG, ie, ALC-1 and BEL-B, respectively. The positive hemagglutination result wa s achieved by this technique. However, in the BEL-5 coated single-particle control system, positive results for both P-hCG and beta subunit hCG soluti on were realized. The occurrence of betamultimer hCG was a causative molecu le revealed by the hemagglutination inhibition technique. Thereby, the nove l method called "combined immunoprecipitation and agglutination" was develo ped to overcome this problem. The free beta subunit together with the betam ultimer hCG were eliminated from other forms presented in P-hCG after using the ALC-1 coated particles. The precipitated particles, which captured the heterodimer hCG molecule, reacted further with soluble BEL-5 to subsequent ly form a trellis. A positive result was obtained only with P-hCG, but not with beta subunit hCG or hLH. This study is inferable as a model for the de tection of heterodimeric molecule by an elementary method.