INTENDED USE

This Human free PSA Kit ELISA Kit is to be used for the in vitro quantitative determination of free Prostate-Specific Antigen (fPSA) concentrations in human serum. The kit is intended for RESEARCH USE ONLY and is not for use in diagnostic or therapeutic procedures.

INTRODUCTION

Prostate Specific Antigen (PSA), also known as . is a 33 KD single-chain serine proteinase. The protein is regulated by androgen, mainly secreted by the epithelial cells of prostate gland. PSA secretion is increased during sexual activity and in conditions such as prostate cancer, prostatitis, and benign prostate hyperplasia. PSA level is also affected by weight, race and height. The major function of the proteinase is to cleave semenogelins in the seminal coagulum. Recently, other function of the protein has been found. PSA exists in serum in at least 3 different forms: free PSA, a-1-anti-chymotrypsin bounded PSA, and a-2 macroglobulin bounded PSA. Free PSA is the unbound form of prostate specific antigen (PSA). Free PSA level increases in aged male population and in prostate inflammatory and hyperplasia individuals. Some studies have suggested that the percentage of free PSA in total PSA is lower in patients with prostate cancer than those with benign prostate hyperplasia. The free to total PSA ratio is being introduced and studied as a biomarker of prostate cancer. Nevertheless, diagnostic and treatment decision should still be based on result of prostate biopsy in combination with the digital rectal exam and/or transrectal ultrasound.

PRINCIPLE OF THE ASSAY

This free PSA enzyme linked immunosorbent assay (ELISA) kit uses a technique called quantitative sandwich immunoassay. The microtiter plate provided in this kit has been pre-coated with a monoclonal antibody specific for free PSA. Standards or samples are then added to the microtiter plate wells and free PSA, if present, will bind to the antibody pre-coated on the wells.

In order to quantify the amount of free PSA present in the sample, a preparation of horseradish peroxidase (HRP)-conjugated PSA antibody is added to each well. The conjugated antibody will bind to the free PSA immobilized on the plate after incubation. All unbound components will be removed by subsequent washing procedure. Next, 3, 3", 5, 5" tetramethyl-benzidine(TMB), a substrate for HRP is added to each well. The colorimetric reaction is proportional to the free PSA content in each well. The reaction is terminated by the addition of a sulphuric acid solution and the colour change is measured spectrophotometrically at the wavelength of 450nm ± 2nm.

In order to measure the concentration of free PSA in samples, this Human Free PSA ELISA Kit includes a set of calibration standards (7 standards). The calibration standards should be assayed at the same time as the samples to allow the operator to produce a standard curve of Optical Density (O.D.) versus free PSA concentration (ng/mL). The concentration of free PSA in the samples is then determined by comparing the O.D. of the samples to the standard curve.

CITATIONS

1. Robitaille CN, Rivest P, Sanderson JT. Antiandrogenic mechanisms of pesticides in human LNCaP prostate and H295R adrenocortical carcinoma cells. Toxicol Sci 2015; 1(143):126-35.