In the clinic, I often receive questions from patients about the interpretation of TSPOT-TB results, and many of them come to the clinic with positive results after having the test performed in other departments of other hospitals where extrapulmonary TB (bone, urinary tract, skin, etc.) is suspected. Patients are very sensitive to this test and are eager to know the significance of this result. The following is the author’s personal opinion. Let’s start with the skin test that we used to use for TB diagnosis but has been gradually replaced by the TSPOT-TB test. The Tuberculin Skin Test (TST) is a traditional method for diagnosing tuberculosis infection that is simple and inexpensive to perform. However, the purified protein derivative (PPD) antigen used in the TST has a complex composition and is susceptible to BCG vaccination and non-tuberculous mycobacterial infection (NTM), and most of the population in China received BCG vaccination during infancy, resulting in its low specificity. In addition, TST lacks sufficient sensitivity in patients with impaired immune function (e.g., HIV-infected patients, patients with severe disease). The γ-interferon-release assays (IGRAs), which are based on the principle of detecting γ-interferon production by T cells stimulated by M. tuberculosis-specific antigens, have overcome the shortcomings of TST. There are many studies suggesting that IGRAs have higher specificity than TST in the diagnosis of M. tuberculosis infection, and there are two kinds of IGRAs that are more mature internationally: one is the application of enzyme-linked immunosorbent assay (ELISA) to detect the level of IFN-γ released from sensitized T cells in whole blood after being stimulated by TB-specific antigen again, which is called whole blood assay or TB infection T cell immunoassay The other is an enzyme-linked immunospot assay (ELISPOT), which measures the number of IFN-γ-releasing effector T cells in peripheral blood mononuclear cells stimulated by M. tuberculosis-specific antigens, and is called a cell-based assay or TB-infected T-cell assay. The two products are similar in principle, but the assay techniques and procedures are slightly different. The specific antigens used are antigenic peptides encoded by the RD1 region of Mycobacterium tuberculosis, including mainly ESTA-6 and CFP-10 antigens or antigenic peptides, to which some products add TB7.7 antigenic peptides. ESTA-6 and CFP-10 are absent in all BCG strains, and in most environmental mycobacteria, and therefore are not affected by BCG inoculation and most non-tuberculous mycobacterial infections (NTM). TB assay is a new method to determine whether a subject is currently infected with Mycobacterium tuberculosis by detecting the presence of TB effector T lymphocytes by enzyme-linked immunospot technique (ELISPOT) using TB-specific antigens (ESTA-6,CFP-10). TB results cannot be used alone or conclusively to diagnose active TB disease. A positive result only indicates the presence of Mycobacterium tuberculosis-specific effector T cells, i.e., that the patient has a tuberculosis infection or that it may be caused by one of the few non-tuberculous mycobacterial infections such as Mycobacterium kansasii, Mycobacterium suis, Mycobacterium gordonii, or Mycobacterium hainanense (NTM). However, the determination of active TB disease needs to be combined with clinical symptoms and other testing indicators. Tuberculosis infection usually manifests as overt infection and latent infection. Overt infection, i.e., active TB, accounts for only a small proportion of all infected persons in most infectious diseases. Latent infection, also known as latent infection, is an infection in which the pathogen is parasitized in certain areas of the body, and the pathogen can be latent for a long time because the body’s immune function is sufficient to confine the pathogen without causing a dominant infection, but not sufficient to remove the pathogen. Latent Tuberculosis Infection (LTBI) has a risk of developing into active TB disease. Active TB and LTBI are distinct stages of Mycobacterium tuberculosis infection, and gamma interferon, which is released by Mycobacterium tuberculosis-specific effector T cells upon specific antigen stimulation as detected by IGRAs, is released in both active TB and latent TB infection (LTBI). The results of several studies have shown that IGRAs can only determine the presence of TB infection, but cannot distinguish between active TB and LTBI, so IGRAs have limited diagnostic value for active TB disease. Negative results suggest that patients do not have effector T cells specific for Mycobacterium tuberculosis. Negative results cannot exclude the possibility of Mycobacterium tuberculosis infection if: 1. false negative results due to different stages of infection (e.g., specimens were obtained before the onset of cellular immunity); 2. a few cases of immune system insufficiency, such as HIV-infected patients, tumor patients, and children; 3. and other immunological and experimental non-normal manipulation differences. In summary, we can not rely too much on the TSPOT-TB test, and its results can only be used as a diagnostic reference basis. And the majority of patients do not need to be too panic because of the positive results of TSPOT-TB.