Tissue Polypeptide Antigen (TPA)

The tissue polypeptide antigen (TPA) has a molecular weight of 17,000 to 43,000 and is composed of three subunits B1, B2 and C, and its activity is mainly at B1. TPA is mainly found in the placenta and most tumor tissues, and serum TPA in patients with various malignant tumors (ovarian cancer, colon cancer, rectal cancer, hepatocellular carcinoma, pancreatic cancer, lung cancer, breast cancer, endometrial cancer, testicular tumor, etc.) The detection rate (positive with >130U/L serum) can range from 20% to 90%, and some people think that it is as high as 80% to 100%. Its presence has no correlation with tumor site and tissue type. Basic Information Specialist classification: Oncology examination classification: other examinations Applicable gender: whether men and women apply fasting: fasting Analysis results: Below normal: normal. Normal value: Serum: 0-120 U/L Above normal: Found in lung cancer, bladder cancer, prostate cancer, breast cancer, ovarian cancer, acute hepatitis, pancreatitis, pneumonia, digestive tract tumors. negative: Positive: Tips: Do not eat too greasy, high-protein foods the day before the blood draw, avoid heavy drinking. The alcohol content in the blood directly affects the test results. Normal value Serum <120 U / L (enzyme-linked immunosorbent assay). (Note the specific reference value depends on each laboratory.) Clinical significance Elevated in lung cancer, bladder cancer, prostate cancer, breast cancer, ovarian cancer, acute hepatitis, pancreatitis, pneumonia, digestive tract tumors. In addition, the positive rate of normal people was 4.7%. However, a considerable number of patients with non-malignant tumors have TPA in their serum, and the positive rate is about 14% to 35%. The following respiratory, hepatobiliary and urinary tract infections are common, so TPA is not a tumor-specific marker. In patients with malignant tumors, the increase in TPA is often persistent, so continuous monitoring is often beneficial for the identification of malignant and non-malignant lesions. As a tumor marker, TPA has the following clinical significance. The preoperative TPA increase is very significant in patients with cancer. It often indicates a poor prognosis. After the treatment is improved, the amount of TPA increases again, suggesting that there is tumor recurrence. Simultaneous detection with CEA can significantly improve the mammary gland. The correctness of cancer diagnosis helps differential diagnosis between malignant and non-malignant breast lesions. Positive results may be diseases: ovarian cancer, breast cancer, bladder cancer, lung cancer 1. Immunohistochemical staining often shows spotted false positive reactions on the sections, which should be noted. 2. Some non-epithelial tumor tissues (leiomyosarcoma) are positively expressed and should be noted at the time of diagnosis. Inspection process The method is divided into three steps, namely antigen-antibody reaction, B and F separation, and radioactivity determination. (1) Reaction of antigen with antibody: The specimen (non-labeled antigen), labeled antigen and antiserum are sequentially dosed into a small test tube, and allowed to stand at room temperature (15 to 30 ° C) for 24 hours to fully compete for binding. (2) Separation of B and F: There are various separation techniques, and the precipitation method is commonly used. 1 second antibody precipitation method: also known as diabody method, after the test antigen specifically reacts with the first antibody, the corresponding second antibody is added, so that the formed antigen-first antibody-second antibody complex is co-precipitated. The labeled antigen B is separated from the free antigen F by centrifugation. This method is a specific precipitation, complete separation, low non-specific binding. However, the amount of the second antibody is large and the cost is high. In addition, the serum concentration and the presence or absence of anticoagulants can affect the results to some extent. 2 Polyethylene glycol (PEG) precipitation method: the protein is in an isoelectric point state, and the hydration layer is destroyed to cause protein precipitation. The advantage of this method is that PEG is convenient to prepare, inexpensive, and rapid to separate. The disadvantage is that there are many non-specific precipitates and the separation is incomplete. 3Second antibody-polyethylene glycol precipitation method: This method not only has the advantage of rapid precipitation of PEG method, but also maintains the effect of specific precipitation of second antibody, reduces the amount of second antibody, and reduces the concentration of PEG, so that non-specific precipitation Reduced material. 4 Activated carbon adsorption method: the free part of small molecules is adsorbed by the surface activity of activated carbon. For example, a layer of dextran is coated on the surface of the activated carbon to make a mesh having a certain pore diameter on the surface, thereby allowing small molecules of free antigen or hapten to escape and being adsorbed, while the macromolecular complex is excluded. After the antigen and the antibody are reacted, the dextran-activated carbon is added and allowed to stand for 5 to 10 minutes, so that the free antigen is adsorbed on the activated carbon particles, and the particles are precipitated by centrifugation, and the supernatant contains the labeled antigen. (3) Determination of radioactivity: After separation of B and F, the radioactivity can be measured. There are two types of measuring instruments: a liquid scintillation counter (measuring beta rays) and a crystal scintillation counter (measuring gamma rays). The unit of counting is the number of electrical pulses output by the detector in units of cpm (number of pulses/min). A standard curve is required for each measurement, and the different concentrations of the standard antigen are plotted on the abscissa, and the corresponding radioactivity measured is plotted on the ordinate. The radioactivity may be optionally B or F, and the calculated values ​​B/B+F, B/F or B/B0 may also be used. Specimens should be determined in duplicate, the average value is taken, and the corresponding antigen concentration is detected on the standard curve. Not suitable for the crowd Not suitable for the crowd: major bleeding, faint fascination. Adverse reactions and risks May be concurrently infected.