Tuberculin

Tuberculin is the name given to extracts of Mycobacterium tuberculosis, M. bovis, or M. avium that is used in skin testing in animals and humans to identify a tuberculosis 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 antigens. Tests based upon PPD are relatively unspecific since many of its proteins are found in different mycobacterial species.

Tuberculin is an outer membrane protein of Mycobacterium species.