tissue polypeptide antigen

Tissue polypeptide antigen (TPA) is a fetal antigen found in proliferating tissues. The content in normal tissues is very small. TPA is recognized by antibodies to cytokeratin 8, 18 and 19. Different proteins with a TPA immunoreactivity have been isolated with a molecular weight of 20 to 45 kD). TPA has extensive co-source with certain cytokinins and cytoskeletal proteins, and its concentration increases when cells divide. TPA is a common tumor marker with no organ specificity. Basic Information Specialist classification: Oncology examination classification: immune examination Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: normal. Normal value: TPA: 0-130U/L Above normal: Found in lung cancer, bladder cancer, prostate cancer, breast cancer, ovarian cancer, acute hepatitis, pancreatitis, pneumonia, digestive tract tumors. negative: normal. Positive: 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. 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 <130U/L. Clinical significance (1) The serum TPA level of lung cancer patients was significantly increased. The level of TPA was positively correlated with clinical stage and lymph node metastasis. It decreased significantly after operation and increased significantly in the early stage of recurrence. It is suggested that the detection of serum TPA has certain clinical significance for the monitoring of lung cancer and the early diagnosis of recurrence. (2) Increased serum TPA can also be found in malignant tumors such as gastric cancer, breast cancer, prostate cancer, bladder cancer, ovarian cancer and cholangiocarcinoma. For example, combined with other tumor markers, early recurrence of the above tumors can be found. (3) In some non-neoplastic diseases such as emphysema, bronchitis, benign liver disease, peptic ulcer, pancreatitis and pregnancy, serum TPA may also increase, but the increase is not as good as malignant tumor. (4) TPA can be used for the differential diagnosis of cholangiocarcinoma and hepatocellular carcinoma. TPA is positive in cholangiocarcinoma and negative in hepatocellular carcinoma. High results may be diseases: metastatic pleural tumor, pancreatic cancer considerations 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 People with reduced hematopoietic function such as leukemia, various anemia, myelodysplastic syndrome, or people with thrombocytopenia should pay attention to blood draw, and should not take more or more blood. Adverse reactions and risks 1. After the blood is drawn, do not press the needle hole to avoid subcutaneous hematoma. If there is a small piece of bruise in the blood, it is slightly tender, please don't panic, you can do hot compress after 24 hours to promote the absorption of blood. The general small amount of congestion will gradually absorb in 3 to 5 days and the color will become lighter and return to normal. 2. After the blood draw, symptoms such as dizziness, vertigo, fatigue, etc. should be immediately supine, drink a small amount of syrup, and then undergo a physical examination after the symptoms are relieved.