Suppression of delayed hypersensitivity to the hapten by induction of tolerance to the carrier.

Delayed hypersensitivity reactions (DHR) and anaphylactic reactions to carrier and hapten determinants were studied in guinea pigs immunized with DNP-mycobacterium and rendered partially tolerant to the carrier by a single intravenous injection of mycobacterium prior to immunization. The results clearly show that the induction of depressed DHR to mycobacterium leads to a suppression of DHR to the hapten while no depression of anaphylaxis to the hapten is observed. It is proposed that the tolerogenic treatment acts at the macrophage level rather than at the T cell level.