Homologous radioimmunoassay for secreted mouse prolactin

A highly specific, homologous radioimmunoassay has been developed for the secreted form of mouse prolactin using hormone isolated and purified from the media from long-term pituitary cultures. Mouse pituitary homogenates and mouse serum give parallel dilution response curves in the assay, and no cross-reaction is seen with either mouse growth hormone or mouse placental lactogen. The assay is sensitive to 40 pg per tube, and the reproducibility and precision of the assay are within acceptable limits. Antiserum generated to secreted mouse prolactin cross-reacts with both the secreted and stored forms of the hormone; however, the secreted form shows greater immunopotency. Secreted prolactin also shows greater immunopotency when compared with stored prolactin using an antiserum generated to the stored form of the hormone.