Tuberculin is the name given to extracts of Mycobacterium tuberculosis
Mycobacterium tuberculosis
Mycobacterium tuberculosis is a pathogenic bacterial species in the genus Mycobacterium and the causative agent of most cases of tuberculosis . First discovered in 1882 by Robert Koch, M...

, M. bovis
Mycobacterium bovis
Mycobacterium bovis is a slow-growing , aerobic bacterium and the causative agent of tuberculosis in cattle...

, or M. avium that is used in skin testing in animals and humans to identify a tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

 infection. Several types of tuberculin have been used for this, of which purified protein derivative (PPD) is the most important. PPD is a poorly-defined, complex mixture of antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...

s. Tests based upon PPD are relatively unspecific since many of its proteins are found in different mycobacterial species.


Tuberculin was discovered by German
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 scientist and physician Robert Koch
Robert Koch
Heinrich Hermann Robert Koch was a German physician. He became famous for isolating Bacillus anthracis , the Tuberculosis bacillus and the Vibrio cholerae and for his development of Koch's postulates....

 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
Clemens von Pirquet
Clemens Peter Freiherr von Pirquet was an Austrian scientist and pediatrician best known for his contributions to the fields of bacteriology and immunology....

,an Austrian physician, discovered that patients who had previously received injections of horse serum or smallpox vaccine
Smallpox vaccine
The smallpox vaccine was the first successful vaccine to be developed. The process of vaccination was discovered by Edward Jenner in 1796, who acted upon his observation that milkmaids who caught the cowpox virus did not catch smallpox...

 had quicker, more severe reactions to a second injection, and he coined the word allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...

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. Individuals with active tuberculosis were usually tuberculin positive, but many of those with disseminated and rapidly progressive of disease were negative. This led to the widespread but erroneous belief that tuberculin reactivity is an indicator of immunity to tuberculosis.
The test used in the United States at present is referred to as the Mantoux test
Mantoux test
The Mantoux test is a diagnostic tool for tuberculosis. It is one of the two major tuberculin skin tests used in the world, largely replacing multiple-puncture tests such as the Tine test...

. An alternative test called the Heaf test
Heaf test
The Heaf test is a diagnostic skin test performed in order to determine whether or not a child has been exposed to tuberculosis. Also known as the Sterneedle test, it is administered by a Heaf gun which is a spring-loaded instrument with six needles arranged in a circular formation.Patients who...

was used in the United Kingdom until 2005, although the UK now uses the Mantoux test in line with the rest of the world. Both of these tests use the tuberculin derivative PPD.

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