Effects of several drugs on the liver injury induced by delayed-type hypersensitivity to picryl chloride by regulating suppressor or helper T cells

The effects of histamine, cimetidine, and diphenhydramine on picryl chlorid e (PCl)-induced ear contact sensitivity, as well as liver injury, were exam ined in mice. Histamine was found to produce less response in mice to PCl. In contrast, cimetidine, a selective antagonist of histamine type 2 recepto r, significantly enhanced the response, while diphenhydramine, a selective antagonist of histamine type 1 receptor showed no effect. The pre-treatment of 2,4,6-trinitrobenzene sulphonic acid (TNBS) significantly caused a tole rance to the formation of the liver injury induced by delayed-type hypersen sitivity (DTH) to PCI. Against the tolerance, the single intravenous admini stration of 150 mg kg(-1) cyclophosphamide (Cy) at 3 days before the TNBS-t reatment recovered the response and induced a remarkable elevation of serum transaminases. On the other hand, cyclosporin A protected the liver injury . These observations revealed that the development of acute PCl-DTH liver i njury was regulated by the functional state of suppressor and helper T cell s. (C) 1999 The Italian Pharmacological Society.