Immunoreactive relaxin-like substance in human seminal plasma.

Large amounts of an immunoreactive relaxin-like peptide were demonstrated in human seminal plasma. The concentrations of this peptide were determined in seven healthy volunteers, and in twenty-eight non-selected male patients seeking advice for sterility. A wide range of immunoreactive relaxin concentrations was observed, varying between 1,240 pg and 73,000 pg of relaxin porcine equivalents per ml of seminal plasma. Given the very special assay medium of seminal plasma, particular attention was paid to the validity of the radioimmunoassay system when applied to this medium.