The tuberculin antigen is injected under the skin to determine if you have ever been exposed to tuberculosis. Also see ppd skin test (mantoux test). The ppd test is a more accurate test than the tine test and is considered the current state of the art test to determine if someone has been exposed to tuberculosis.

The tuberculosis antigen is injected just under the skin with a multiple-pronged instrument. The antigen is located on the tines (spikes) that penetrate the skin. The site is labeled, usually with an ink pen, and it is usually done on the arm.

After 48 to 72 hours, if the test is positive, the skin will appear red and swollen like a mosquito bite where the antigen was injected. A negative test may be a bit red but will not be swollen and firm like a mosquito bite.

There is no special preparation. People with dermatitis or other skin irritations may have the test performed at different locations on the body.

When the antigen is injected, there is a slight stinging sensation where the tines are inserted. After the reaction begins, the area may itch or burn.

This test is very helpful in determining if you have ever been exposed to tuberculosis. If you have been exposed to tuberculosis at any time in the past, antibodies are formed by your body and remain in your system; when the tuberculosis antigen is injected under the skin during the tine test, your body will have an immune response, and there will be an area of inflammation at the site of the injection.

No inflammation would appear after the injection if you have never been exposed to tuberculosis.

An inflammation zone indicates the immune system recognizes the antigen, and your body has been exposed to the bacteria that cause tuberculosis at some point in your life. A positive TB tine test does not mean that you have active tuberculosis, only that your body has been exposed at some point. After exposure all future TB tine tests will be positive.

If you have a positive TB tine test, the Centers for Disease Control recommends that you should have a PPD, unless the first tine test had a blistering or very large reaction. A chest X-ray will be taken to evaluate if you have active tuberculosis or not.

A very small amount of the antigen is injected, so the risks are minimal. Typical reactions include itching and hives. Sometimes, the area may blister. Rarely, the swelling may become very large; you should let your health care provider know if that happens.

The test may be falsely negative in the elderly and in patients with weakened immune systems, such as those with AIDS, those with cancer undergoing chemotherapy, those who have had an organ transplant, and those on high dose steroids.