In situ immunopathological changes in cutaneous leishmaniasis due to Leishmania donovani

Introduction Cutaneous leishmaniasis in Sri Lanka is a newly established parasitic disease caused by the usually visceralizing Leishmania donovani. Skin lesions manifest as non-itchy, non-tender papules, nodules or ulcers. In situ cytokine expression provides clues for immunopathogenesis of this localized form of disease. Methods Skin biopsies from 58 patients were analyzed for histological appearance and in situ cytokine expression of T- helper 1 (Th1) and T- helper 2 (Th2) cytokines, namely interferon (IFN)-γ, interleukin (IL)-12A, tumor necrosis factor (TNF)-α, IL-4 and IL-10 by real-time RT- PCR. Results Significant up regulation of the Th1 cytokine IFN-γ and down regulation of the Th2 cytokine IL-4 was seen in patients compared to healthy controls. Significantly elevated tissue expression of IFN-γ and TNF-α was seen in lesions that presented later than 6 months from the time of onset, while IL-4 expression was more prominent in lesions that responded poorly to antimony therapy. Conclusion A prominent Th1 response appears to support resolving of lesions, whereas a Th2 biased milieu tends to favor poor responsiveness to antimony and delayed lesion healing in L. donovani infections in Sri Lanka. This article is protected by copyright. All rights reserved.