用纯化的抗体包被微孔板，制成固相载体，往包被抗CCSA-3抗体的微孔中依次加入标本或标准品、生物素化的抗CCSA-3抗体、HRP标记的亲和素，经过彻底洗涤后用底物TMB显色。TMB在过氧化物酶的催化下转化成蓝色，并在酸的作用下转化成最终的黄色。颜色的深浅和样品中的CCSA-3呈正相关。用酶标仪在450nm波长下测定吸光度（OD值），计算样品浓度。
Intended use
This immunoassay kit allows for the for the in vitro quantitative determination of human colon cancer-specific antigen-3, CCSA-3 concentrations in cell culture supernates, serum, plasma and other biological fluids.
Introduction
Two colorectal cancer-specific proteins, colon cancer–specific antigen (CCSA)-3 and CCSA-4, have shown promise as markers for detecting both colorectal cancer and precancerous lesions. CCSA-3 and CCSA-4 displayed a high degree of accuracy in identifying patients with preneoplastic and neoplastic lesions.
Test principle
The microtiter plate provided in this kit has been pre-coated with an antibody specific to CCSA-3. Standards or samples are then added to the appropriate microtiter plate wells with a biotin-conjugated polyclonal antibody preparation specific for CCSA-3 and Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. Then a TMB substrate solution is added to each well. Only those wells that contain CCSA-3, biotin-conjugated antibody and enzyme-conjugated Avidin will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the color change is measured spectrophotometrically at a wavelength of 450 nm ± 2 nm. The concentration of CCSA-3 in the samples is then determined by comparing the O.D. of the samples to the standard curve.
