The Mantoux skin test is an example of which type of hypersensitivity reaction?

The Mantoux skin test, also known as the tuberculin skin test, is a classic example of a Type IV hypersensitivity reaction. This type of hypersensitivity is characterized by a delayed immune response mediated by T cells rather than antibodies.

In the Mantoux test, purified protein derivative (PPD) from the Mycobacterium tuberculosis bacteria is injected intradermally. If the individual has been previously sensitized to the bacteria, T cells recognize the PPD and mount an immune response, leading to local inflammation, redness, and swelling at the injection site after 48 to 72 hours. The response is not immediate, which is a hallmark feature of Type IV hypersensitivity.

In contrast to other types of hypersensitivity, which involve antibodies (like Types I, II, and III), Type IV is strictly cell-mediated. This distinction is crucial in understanding the various mechanisms of immune responses and their implications in diagnostics and therapies. Therefore, recognizing the Mantoux test as a Type IV hypersensitivity is essential for comprehending how the body responds to certain pathogens and the role of T cells in immunological reactions.