Tuberculin

Overview
Tuberculin is an antigen used to aid in the diagnosis of tuberculosis infection. An infection with the bacterium that causes tuberculosis frequently leads to a sensitivity to these antigens. Tuberculin was discovered by German scientist and physician Robert Koch in 1890.

The original tuberculin discovered by Koch was a glycerine extract of the tubercle bacilli and was developed as a remedy for tuberculosis, but it was ineffective in this role. Clemens von Pirquet discovered that patients who had previously received injections of horse serum or smallpox vaccine had quicker, more severe reactions to a second injection, and he coined the word allergy to describe this hypersensitivity reaction. Soon thereafter von Pirquet discovered the same type of reaction took place in those infected with tuberculosis, and he thus found the utility of what would become the tuberculin skin test. The test used in the United States at present is referred to as the Mantoux test, in the United Kingdom it is referred to as the Heaf test. Both of these tests use "Purified Protein Derivative", or "PPD", which is a tuberculin derivative.