Abstract

Tuberculin skin testing is a useful technique that has been extensively used for the diagnosis of tuberculosis lately. Stimulation of lymhocytes with PPD is known to be a sensitive in vitro test that can be ıtsed besides skin testing although it is not that common in clinical practice. During the evaluation of these techniques, special attention should be spent on the circumstances that result in false negative or positive skin tests and besides, irrelevant results that can be due to incomplete standardization of in vitrotests should be helt in mind.