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Pathology Hypersensitivity 9a4ba3d1

The tuberculin test is associated with all of the following except:

A
Indicates the cell mediated immunity against the bacteria
B
Likely to be positive in prior exposure to mycobacteria
C
Can distinguish between infection and disease
D
May be false negative in immunosuppression
High-Yield Explanation
Tuberculin test/ Mantoux test: The PPD test determines if someone has developed an immune response to the bacterium that causes tuberculosis. The standard recommended tuberculin test is the Mantoux test, which is administered by injecting a 0.1 mL of liquid containing 5 TU (tuberculin units) PPD (purified protein derivative) into the top layers of skin of the forearm. Doctors should read skin tests 48-72 hours after the injection. The basis of the reading of the skin test is the presence or absence and the amount of induration (localized swelling). A negative test does not always mean that a person is free of tuberculosis. A person who received a BCG vaccine against tuberculosis may also have a positive skin reaction to the TB test. A positive tuberculin skin test result signifies cell-mediated hypersensitivity to tubercular antigens, but does not differentiate between infection and disease. False-negative reactions (or skin test anergy) may be produced by ceain viral infections, sarcoidosis, malnutrition, Hodgkin lymphoma, immunosuppression, and (notably) overwhelming active tuberculous disease. False positive reactions may result from infection by atypical mycobacteria.

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