Antigen testing is commonly used to detect infectious diseases and more. The main function of antigen testing is to detect the presence of antigens in the body in order to diagnose pathogen infections, tumors, blood groups, and more. When the body is infected by various pathogens, it may result in the presence of pathogen antigens in the blood. With antigen testing, it is possible to diagnose whether a patient is infected with a pathogen. For example, Mycoplasma antigen will produce a positive result when diagnosing serum after Mycoplasma infection. When there is a tumor in the body, it can aid in the diagnosis of the tumor by testing for tumor-specific antigens. For example, an alpha-fetoprotein test can help diagnose liver cancer. Red blood cells in human blood are also antigens. Therefore, individual blood groups can be determined by antigen-antibody agglutination reactions and antigen testing. Before testing, consult your doctor on a case-by-case basis and choose the test on your doctor’s advice.