Human PSA ELISA Kit

INTENDED USE

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

INTRODUCTION

Prostate-Specific Antigen (PSA) is a single-chain glycoprotein weighing approximately 34 kDa.
PSA is a secretion of the prostate epithelium produced by normal, benign, and cancerous cells.
PSA is functionally and immuno-chemically distinct from Prostatic Acid Phosphatase. Development of an enzyme immunoassay has made it possible to accurately detect low concentrations of PSA in the blood of patients with malignant and benign prostate disease. PSA serum levels are elevated in patients with prostate cancer, benign prostatic hypertrophy (BPH) and inflammatory conditions associated with the surgical stage and metastasis of the disease. After several years of clinical use, PSA has emerged as the choice overall serum marker for prostate cancer. Furthermore, numerous investigators consider PSA to be the most useful and meaningful tumour marker in cancer biology.
PSA is a useful serum marker for prostate cancer and represents a valuable new tool for the clinician. When used in combination with the digital rectal exam and/or transrectal ultrasound, PSA may assist in early detection programs for prostate cancer. Additionally, costly and time-consuming bone scans can be avoided for patients with newly diagnosed and untreated prostate cancer. The latter assumes a negative bone scan and therefore, a staging bone scintigram may not be necessary. Finally, an ultra-sensitive PSA assay would be useful when monitoring patients for residual disease following radical prostatectomy, as well as earlier detection of recurrent active disease following such therapies.

PRINCIPLE OF THE ASSAY

This PSA enzyme linked immunosorbent assay (ELISA) applies a technique called a quantitative sandwich immunoassay.
The microtiter plate provided in this kit has been pre-coated with a monoclonal antibody specific for PSA. Standards or samples are then added to the microtiter plate wells and PSA, if present, will bind to the antibody pre-coated on the wells. In order to quantify the amount of PSA present in the sample, a standardized preparation of horseradish peroxidase (HRP)-conjugated monoclonal antibody, specific for PSA are added to each well to “sandwich” the PSA immobilized on the plate. The microtiter plate then undergoes incubation, followed by thorough washing of the wells to remove all unbound components. Next, a TMB (3,3′,5,5′ tetramethyl-benzidine) substrate solution is added to each well. The enzyme (HRP) and substrate are allowed to react over a short incubation period. Only those wells that contain PSA and enzyme-conjugated antibody will exhibit a change in colour. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the colour change is measured spectrophotometrically at a wavelength of 450nm ± 2nm.
In order to measure the concentration of PSA in the sample, this Human PSA ELISA Kit includes a set of calibration standards (6 standards). The calibration standards are assayed at the same time as the samples allowing the operator to produce a standard curve of Optical Density (O.D.) versus PSA concentration (ng/mL). The concentration of PSA in the samples is then determined by comparing the O.D. of the samples to the standard curve.