Description(s):
CA125 is a membrane associated glycoprotein that is produced on the surface of cells. The extracellular region of CA125 can be released from the cell surface and into the blood by undergoing proteolytic cleavage. CA125 is a key diagnostic marker for ovarian cancer, but it may also be elevated in other types of cancer including fallopian tube cancer, lung cancer, breast cancer, and gastrointestinal cancer. Since multiple cancer types can cause an increase in serum levels of CA125, this protein is not used to detect cancer in general. However, CA125 is often monitored to track disease progression in ovarian cancer patients and evaluate their responses to chemotherapy.
Principle
The wells of the plate are coated with capture antibody specific to CA125. In this assay, the test sample initially reacts with the solid phase capture antibody, resulting in CA125 being bound to the well. The wells are then washed to remove unbound proteins, and biotin-linked antibodies are added to bind to the immobilized CA125. After washing away the unbound antibodies, Streptavidin-HRP conjugate is added to form a complex with the antibody-bound CA125. After incubation, the wells are washed to remove unbound Streptavidin-HRP conjugate. TMB substrate is then added and forms a blue color when the HRP-linked antibodies are detected. The reaction is then terminated with Stop Solution, which changes the color from blue to yellow. The CA125 concentration in each well is directly proportional to its color intensity and can be quantified by measuring its optical density at 450 nm (OD450) in a microplate reader.
