PENTOXIFYLLINE SUPPRESSES IRRITANT AND CONTACT HYPERSENSITIVITY REACTIONS

Pharmacologic suppression of the effector phase of contact hypersensit ivity appears to have major relevance with regard to treatment of type IV reactions like contact dermatitis. Recently, tumor necrosis factor alpha has been shown to be a critical mediator in hapten-induced irri tant and contact hypersensitivity reactions, thus offering new possibi lities, for therapeutic intervention. Pentoxifylline, a methylxanthine derivative used in the treatment of vascular disorders, currently has been found to suppress the production of tumor necrosis factor alpha by human and murine leukocytes. Therefore, the effect of pentoxifyllin e on the elicitation phase of contact hypersensitivity was studied. In traperitoneal injection of pentoxifylline into sensitized Balb/c and C 3H/HeN mice before application of the challenging hapten dose resulted in a significant reduction of the outcome of the contact hypersensiti vity reaction. The suppressive effect of pentoxifylline was dose depen dent and maximally pronounced upon injection 3 h before hapten applica tion. In contrast to the effector phase of contact hypersensitivity, i nduction of contact hypersensitivity was not affected by pentoxifyllin e when injected into naive mice before performance of sensitization. I n addition, irritant dermatitis induced by 1% croton oil or 5% benzalk onium chloride was suppressed by pentoxifylline as well. These data su ggest a potential pharmacologic intervention with pentoxifylline as a means to treat contact dermatitis.