Red cell-labelled monoclonal antibodies for assay of human chorionic gonadotropin and luteinising hormone by reverse passive haemagglutination.

The assay of human chorionic gonadotropin and luteinising hormone by reverse passive haemagglutination reaction, using monoclonal antibodies coupled to red cells, is described. Quantitation is achieved by end-point determination for serial dilutions of standard or sample, the haemagglutination reaction being observed after settling under gravity for 90 min. Red cell-labelled antibodies were stabilised with glutaraldehyde without loss of sensitivity and allowing long term storage. Various antibody combinations were assessed, and the best combination under optimum conditions gave a positive haemagglutination reaction down to 0.2 ng/ml with HCG.