This assay employs the sandwich enzyme immunoassay technique for the detection of prolactin in human plasma and milk samples. The microtiter plate is coated with affinity purified prolactin antibody. Human Prolactin in samples or standards will react with antibody coated on the microtiter plate. After washing, a biotin-labeled polyclonal anti-Human Prolactin antibody is added and bound to the captured prolactin on the microtiter plate. Excess antibody is washed away and bound primary antibody is reacted with a Streptavidin conjugated to horseradish peroxidase (HRP). Following an additional washing step, TMB is added in the wells. HRP catalyzes TMB substrate solution, resulting in the development of a blue color. The color development is inhibited by the addition of a stop solution, and the color turns yellow. The yellow color is measured at 450 nm. The concentration of prolactin in test sample is directly proportional to the color intensity, which can be determined by extrapolation to the standard curve. Sample Types: plasma and milk. Range: 0.25 - 100 ng/ml. Sensitivity: 0.138 ng/ml. Time: 2 hours ? Prolactin which is a secreted hormone is a growth regulator for many tissues, including cells of the immune system. It may also play a role in cell survival by suppressing apoptosis, and it is essential for lactation. Alternative splicing results in multiple transcript variants that encode the same protein. Prolactin acts primarily on the mammary gland by promoting lactation.