The tuberculin skin test, or PPD test, is based on

Question

Quizplus · Accepted Answer

The PPD test is based on delayed hypersensitivity cell-mediated immunity to certain antigenic components of Mycobacterium tuberculosis. When the purified protein derivative (PPD) from M. tuberculosis is injected under the skin, it triggers a delayed-type hypersensitivity reaction in individuals who have been previously exposed to the organism. This results in the formation of a local inflammatory reaction at the injection site, which can be measured and used to diagnose tuberculosis infection. There is no injection of M. tuberculosis or antigen-antibody reactions occurring at the injection site. Thus, only choice A is correct.

The Tuberculin Skin Test, or PPD Test, Is Based on