Histamine metabolism in delayed type hypersensitivity ? Comparative analysis with cellular infiltrates

Abstract

We examined the dynamic changes of histamine metabolism and infiltrating cell populations in lesional sites of representative cutaneous delayed type hypersensitivity (DTH), including dinitrochlorobenzene (DNCB) allergic dermatitis, purified protein derivative of tuberculin (PPD) reaction, and keyhole limpet homocyanin (KLH)-induced cutaneous basophil hypersensitivity. The concentration of histamine increased with time in all DTH reactions examined, though the time course varied among these reactions. In DNCB allergic dermatitis, the maximum content of the amine at 3 days after the initiation was about three times that of the control baseline. In PPD reaction, the maximum content and the time course were almost similar to that in DNCB allergic dermatitis. However, in KLH-induced cutaneous basophil hypersensitivity the maximum content was about ten times that in DNCB allergic dermatitis or PPD reaction, and was observed earlier, on the 2nd day. There was no remarkable change in the activities of histamine-degrading enzymes in these reactions. There was little infiltration of mast cells, while time-dependent changes of the basophil infiltration were almost parallel those of the histamine concentration in all these reactions. Basophils in DNCB allergic dermatitis showed a piecemeal degranulation, while those in either the PPD reaction or KLH-induced cutaneous basophil hypersensitivity remained intact. These results clearly suggest that the increase of histamine concentration in cutaneous DTH depends on the number of basophils infiltrating the lesional sites, even if the regulatory mechanisms of the activation of the cells differ among the DTH reactions.