Laser - ExcitedImmunofluorometricAssayof Prolactin , with Use of Antibodies

We describe an immunofluorometric assay for prolactin based on lanthanide labelingof a monoclonalantibody and measuring time-resolved fluorescence. In this “sandwich”type assay, the label (Eu3) was bound to the second antibody by means of a simple, rapid method involving the anhydride of diethylenetriaminepentaacetic acid. To measure the photoluminescence of europium (or other lanthanides), we have developed a time-resolved fluorometer with a nitrogen laser as the pulsed excitation source. During the assay, the solid-phase antibody immobilized inside a polystyrene tube is incubated with the plasma sample and the second antibody in a one-step procedure. Results for 67 human plasmas correlated well (r = 0.98) with those by an immunoradiometricmethod.