Gamma Interferon Assays Used in the Diagnosis of Tuberculosis

Tuberculosis (TB) is an ancient disease that has infected humans for thousands of years. However, despite diagnostic tests that detect the disease and effective therapy, there are still millions of people worldwide who are infected with TB. The first TB test used to detect infected patients was a skin test that identifies individuals actively infected with TB. This test used a mix of proteins from culture filtrates of the bacteria Mycobacterium tuberculosis. Recently, two new diagnostic tests have been introduced; these two new tests can detect TB infection in patients by challenging peripheral blood cells with specific TB proteins. These assays measure the cellular immune response to these proteins. This minireview evaluates the new assays and compares them to the use of the TB skin test. The use of these new assays may have some advantages in detecting individuals with active tuberculosis. However, there is still a role for the use of the skin test, especially in young patients.