Rapid radioimmunoassay of progesterone in unextracted bovine plasma

A rapid radioimmunoassay for determining progesterone levels in unextracted bovine plasma has been developed. Two antisera have been tested, anti-deoxycorticosterone-21-hemisuccinate human serum albumin and antiprogesterone-11-hemisuccinate bovine serum albumin. The usefulness of an antiserum for rapid assays has been based on its agreement with assays of organic extracts or chromatographically purified extracts of selected bovine samples. To avoid large blank effects and non-specific interference, a plasma volume of 20 microliter that provided adequate sensitivity was not exceeded. All correlations between rapid assays, assays using organic extraction or assays after chromatographic purification were greater than 0.9 and showed regression slopes approximating unity. It was concluded that individual lots of antisera should be evaluated thoroughly before use in a rapid assay.