By the anamnestic reaction of tuberculin is meant the remembering reaction or, more literally, the reawakening of a dormant tuberculin allergy.
Retesting of groups after varying periods frequently discloses that a small percentage of those who previously reacted positively now react negatively. These persons are said to be in a state of anergy. Their allergy to tuberculin is dormant.
That such variations in tuberculin allergy exist, not only from month to month but from day to day, is commonly accepted. Many factors have been suggested as influencing this fluctuation in sensitivity to tuberculin. Appel and others1 mentioned the age of the lesion, the stage of the infection (progressive or healing), the introduction of tuberculin as causing increased or decreased sensitivity and possibly induced sensitization. Other authors have pointed out that anergy may be present in an advanced stage of tuberculosis or with other diseases, such as measles or any