| Drug Name: |
Tuberculin Purified Protein Derivative |
| Applications: |
Indicated as a diagnostic agent in Mantoux Test used to detect infection with Mycobacterium tuberculosis. |
| Examples of Clinical Use: |
Mycobacterium tuberculosis infection |
| Pharmacodynamics: |
It is intradermally administered to facilitate detection of active tuberculosis caused by Mycobacterium tuberculosis. Tuberculin PPD is an inactivated purified protein fraction obtained from human strain of Mycobacterium tuberculosisand antigen that induces a delayed hypersensitivity response after few hours following administration. When the person has already acquired the tuberculin antigen, the immune response is stimulated to produce antigen-specific T cells that circulate in the bloodstream for up to several months and years. Clinically, a delayed hypersensitivity reaction to tuberculin is a manifestation of previous infection with M tuberculosis or a variety of non-tuberculosis bacteria. In most cases sensitization is induced by natural mycobacterial infection or by vaccination with BCG Vaccine. The antigen causes, pain, edema and infiltration of immune cells in the injection area. |
| Mechanism of action: |
When exposed to M. tuberculosis antigen, the sensitization initiates in the regional lymph nodes where T lymphocytes proliferate in response to the antigenic stimulus to give rise to specifically sensitized lymphocytes which may exist in the circulation up to many years. Antigen is presented to T cells by being ingested by antigen presenting cells (APC), which then present it on their surface to lymphocytes in combination with various MHC molecules once they reach local lymph nodes. Tuberculin PPD most likely interacts with toll-like receptor 2 expressed on APCs that initiates an inflammatory response. Subsequent restimulation of these sensitized lymphocytes with the same or a similar antigen, such as the intradermal injection of tuberculin PPD, evokes a local reaction mediated by these cells. This reaction is referred to as a delayed-type hypersensitivity response that includes vasodilation, edema, and the infiltration of lymphocytes, basophils, monocytes, and neutrophils into the site of antigen injection. The sensitized antigen-specific T lymphocytes proliferate and release lymphokines, which mediate the accumulation of other cells at the site. In vitro studies show that Tuberculin PPD promotes the upregulation of vascular endothelial growth factor (VEGF) expression in T lymphocytes through major histocompatibility (MHC) class II interaction with CD4+ T lymphocyte interaction. The reactions are evident after 5-6 hours following administration. |
| Affected organisms: |
Not Available |
| Targets: |
Target 1. Toll-like receptor 2 |
