CELLULAR OR DELAYED-TYPE HYPERSENSITIVITY (DTH) CAN BE ASSESSED BY INTRACUTANEOUS TESTING WITH BACTERIAL, VIRAL AND FUNGAL ANTIGENS TO WHICH MOST HEALTHY PERSONS ARE SENSITIZED. A POSITIVE SKIN TEST DENOTES PRIOR ANTIGENIC EXPOSURE, T-CELL COMPETENCY AND AN INTACT INFLAMMATORY RESPONSE (1,2) THE REACTION USUALLY PEAKS 48 HOURS AFTER ANTIGEN IS INTRODUCED INTO THE SKIN AND IS MANIFEST AS INDURATION AT THE TEST SITE.
RECALL ANTIGENS MAY BE USEFUL IN EVALUATING DELAYED-TYPE HYPERSENSITIVITY BY ELICITING POSITIVE INDURATION REACTIONS 48 TO 72 HOURS AFTER INTRACUTANEOUS ADMINISTRATION.