What does anti-TP positive mean

Anti-TP positivity means that the human body is infected with syphilis and is the main indicator for diagnosing infection, but it cannot tell the patient's infection level. If we detect anti-TP positivity, at this time, you need to do a thorough investigation to determine the level of syphilis infection. Once you show symptoms of syphilis, we believe that every patient will be very worried. This is a rather difficult disease. If you want to cure syphilis, you still need to actively cooperate with the doctor's treatment.

When a person is infected with syphilis, two types of antibodies are produced in the body. One type is specific anti-Treponema pallidum antibodies, which are indicators for diagnosing infection, but cannot reflect the patient's infection status and will persist for a long time even after being cured. The other type is anti-lipidoid antibodies. The TRUST and RPR mentioned above are antibodies produced against lipids rather than directly against Treponema pallidum, so they are not specific.

In other words, any disease that can cause the production of lipid antibodies in the body can cause the test to produce a positive result, resulting in a false positive. The false positive rate of syphilis serological examination in the elderly is higher than that in the normal population, especially in the elderly over 70 years old with cardiovascular and cerebrovascular diseases, diabetes and leukemia. False positives in TRUST, RPR and TPPA often occur simultaneously. Common causes include:

1. The elderly have declining physical functions and often have some underlying diseases, such as cardiovascular disease, diabetes and cancer. These diseases may cause the body to release cross-antigens that induce the production of anti-lipid antibodies and (or) anti-TP antibodies.

2. Samples from elderly patients contain factors that interfere with immunoassays. The immune regulation function of the elderly is reduced, and they are often accompanied by diseases such as rheumatoid arthritis, upper respiratory tract infection, chronic nephritis, etc. They are more likely to produce some autoantibodies, heterophilic antibodies, rheumatoid factors, abnormal proteins and other cross-reacting substances, which interfere with the test results and cause false positives.

3. The spirochetes that coexist with humans may induce the production of cross-reactive antibodies against specific antigens. Although TPPA is a specific test directly targeting Treponema pallidum, it also has a 1% false positive rate in the general population.

4. During clinical testing, the blood sample may not be completely coagulated, that is, it may be centrifuged or centrifuged incompletely, and fibrin may be adsorbed on the microplate, resulting in an increase in absorbance; the blood sample may be hemolyzed, and various enzymes and active substances in the cells may non-specifically bind to the substrate, resulting in false positive results.

So, what situations can lead to false positives?

(1) False positive for specific antibodies: ① Once infected with or exposed to Treponema pallidum, but the symptoms were relatively mild and not noticed, and the patient recovered without treatment; ② Common medical diseases in the elderly, such as coronary heart disease, cerebrovascular disease, diabetes and leukemia; ③ Symbiotic spirochetes in the human body may induce the production of cross-reactive antibodies against specific antigens; ④ Pregnancy; ⑤ Rheumatoid arthritis, lupus erythematosus, colon cancer, lymphosarcoma, hepatitis C, cirrhosis, AIDS, leprosy, genital herpes, heroin addiction, etc.

(2) Non-specific antibody false positives: ① Acute biological false positive reactions: viral diseases such as rubella, measles, chickenpox, infectious mononucleosis, viral hepatitis, etc.; ② Chronic biological false positive reactions: leprosy, systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, Hashimoto's thyroiditis, polyarteritis nodosa, rheumatic heart disease and heroin addicts, etc.; ③ Other diseases that can lead to the production of lipid antibodies.