Human CA19-9 ELISA Kit

INTENDED USE

This Human CA19-9 ELISA Kit is to be used for the in vitro quantitative determination of human CA19-9 concentrations in serum, plasma, and tissue supernatant. This kit is intended for LABORATORY RESEARCH USE ONLY and is not for use in diagnostic or therapeutic procedures.

INTRODUCTION

Carbohydrate antigen 19-9 (CA19-9), a tetrasaccharide also known as sialyl Lewisᴬ, is abundantly expressed on the surface of pancreatic cancer cells, as well as on the surface of colorectal and other cancer cells. Serum CA19-9 usually ranges from 0 to 37 units per milliliter in healthy population. Higher than normal level is often an indication of cancer in the pancreas, gallbladder, liver, lung, or colon. Serum CA19-9 is an extensively validated, and currently, the most important biomarker available for monitoring pancreatic cancer progression and regression. CA19-9 serum levels have been applied clinically for predicting chemotherapy response, post operational recurrence, survival rate statistics and other prognostic information. It is worthy of note that pancreatic cancers with a Lewis-negative phenotype (5–10%) can produce false-negative results. This CA19-9 ELISA kit uses a pair of monoclonal antibodies that was developed by immunization with CA19-9 expression cancer cell line SW1116 and screened with highly purified reference-grade native CA19-9, thus warranting assay specificity. The performance data of this kit demonstrated high accuracy and sensitivity, and low coefficient of variation.

This CA19-9 ELISA is a 2.5-hour solid phase enzyme linked immunoassay readily applicable to measure CA19-9 in serum, plasma, and cell culture supernatant. This CA19-9 ELISA is expected to be effectively used for further investigations into the relationship between CA19-9 and the various conditions mentioned above.

PRINCIPLE OF THE ASSAY

This CA19-9 enzyme-linked immunosorbent assay (ELISA) applies a technique called quantitative sandwich immunoassay. The microtiter plate provided in this kit has been pre-coated with a monoclonal antibody specific for CA19-9. Standards or samples are then added to the appropriate microtiter plate wells and incubated. CA19-9, if present, will bind and become immobilized by the antibody pre-coated on the wells. The microtiter plate wells are thoroughly washed to remove any unbound CA19-9 and other components of sample. In order to quantitate the amount of CA19-9 present in the sample, a horseradish peroxidase (HRP)-conjugated monoclonal antibody specific for CA19-9 is added to each well to “sandwich” the CA19-9 immobilized during the first incubation. The microtiter plate then undergoes a second incubation. The wells are thoroughly washed to remove all unbound HRP-conjugated antibodies and a TMB (3,3′,5,5′ tetramethyl-benzidine) substrate solution is added to each well. The enzyme (HRP) and substrate solution are allowed to react over a short incubation period. The wells that contain CA19-9 will exhibit blue colour. The enzyme-substrate reaction is terminated by the addition of sulphuric acid solution and the colour will change to yellow. The optical density will be measured spectrophotometrically at a wavelength of 450 nm ± 2 nm.

In order to measure the concentration of CA19-9 in the samples, the provided standard is diluted (2-fold) with the appropriate Calibrator Diluent and assayed at the same time. This allows the operator to produce a standard curve of Optical Density (O.D) versus CA19-9 unit/mL (U/mL). The concentration of CA19-9 in the samples is then determined by comparing the O.D. of the samples to the standard curve.