Enzyme immunosorbent assay of prolactin with penicillinase as label

This competitive, rapid, and sensitive enzyme immunosorbent assay for measuring human prolactin in plasma involves penicillinase (EC 3.5.2.6) as label. Microtiter plate wells coated with goat anti-rabbit gamma globulin are filled with antibody to prolactin and plasma sample or reference prolactin and incubated with penicillinase-labeled prolactin for 1 h at 37 degrees C. The enzyme activity of the bound complex is then measured. The assay is as sensitive as radioimmunoassay, the detection limit being 2.5 ng of prolactin per milliliter of plasma. The plasma prolactin values obtained by enzyme immunoassay correlated well with those determined by radioimmunoassay: r = 0.98, slope = 1.00, intercept = 1.11 ng/mL (n = 53).