Dinitrochlorobenzene is genotoxic by sister chromatid exchange in human skin fibroblasts

Dinitrochlorobenzene (DNCB) is clinically efficacious in the therapy of alopecia areata, but its use was limited when it was found to be mutagenic in the Ames test. However, there has been renewed interest in the immunomodulatory benefits of topically applied dinitrochlorobenzene in patients with human immunodeficiency virus and systemic lupus erythematosus. The current study examines the genotoxicity of dinitrochlorobenzene in human skin fibroblasts using sister chromatid exchange. Dinitrochlorobenzene caused a significant increase in sister chromatid exchange at concentrations ranging from 2.5 to 10 mu M. Thus, dinitrochlorobenzene is genotoxic in human skin fibroblasts at concentrations well below those used clinically. The potential for long-term toxicity from dinitrochlorobenzene will have to be weighed against the severity and prognosis of the diseases for which it is used.