Short report: persistence of tumor necrosis factor-alpha in situ after lesion healing in mucosal leishmaniasis.

Mucosal leishmaniasis (ML) is a disease characterized by intense activation of inflammatory cells and extensive tissue destruction. Among the cytokines involved in the immune response to ML, tumor necrosis factor-alpha (TNF-alpha) has attracted strong interest because of its roles in the modulation of the immune response. We studied 20 patients with ML who provided biopsy specimens before treatment and after lesion healing obtained by specific therapy. The biopsy specimens were subjected to immunohistochemical analysis for in situ quantification of cellular and extracellular TNF-alpha. The amount of TNF-alpha was significantly lower in the healed lesions compared with pretreatment biopsy specimens, although TNF-alpha persisted at the tissue level even after lesion healing. This relevant finding demonstrates for the first time an in situ tissue reduction of TNF-alpha after treatment and shows persistence of TNF-alpha in healed lesions may be related to the maintenance of an immunopathologic background for relapses observed in ML.