Human chorionic gonadotrophin in human seminal plasma as shown with assays using monoclonal antibodies.

Human chorionic gonadotrophin (hCG) has been estimated in 79 samples of human seminal plasma using three different methods. The Serono "ter" double antibody-polyethylene glycol "hCG-beta" radioimmunoassay, which uses a polyclonal antibody and estimates intact HCG plus free beta-subunit, gave concentrations of 37 +/- 21 (18-112) mIU/ml 1st IRP 75/537 (n = 46). Concentrations were much less with assays that utilised monoclonal antisera. The Pharmacia-LKB "DELFIA" fluoroimmunoassay, which estimates intact hCG only, failed to detect hCG in 16/76 (21%) of samples and detected only a trace (less than 2 mIU/ml) in 32 samples, but was able to estimate authentic hCG in 28 samples, the highest concentration being 25 mIU/ml. The proportion monoclonal/polyclonal hCG in these samples was highly variable at 4-122 (mean 37) %. The. Medgenix oligo-monoclonal immunoradiometric assay, which estimates intact hCG plus free beta-subunit more specifically, gave even lower concentrations. It failed to detect hCG in 6/54 (11%) of samples and detected only a trace in 27 samples, but was able to estimate hCG in 21 samples, the highest concentration being 20 mIU/ml. The proportion of monoclonal/polyclonal hCG in no case exceeded 0.2%. It is concluded that authentic hCG does occur in human seminal plasma, but only in about a third of samples. The origin of this hCG is discussed.