Immunology of leishmaniasis

Abstract

Resolution of leishmanial infection is dependent on the coordinated interactions between components of cell mediated immune response, central to which is the activation of targeted T-cell populations for appropriate cytokine production and activation of infected cells. In human as well as murine leishmaniasis, cure is associated with predominant Th1 response, good cell-mediated immunity (CMI), production of interferon gamma (IFN-γ) and macrophage activation. On the other hand, cytokine analysis in visceral leishmaniasis reveals enhanced induction of IL-10 and⁄or IL-4 mRNA in tissues, poor CMI, hypergammaglobulinaemia and enhanced presence of IL-4 in circulation of patients with progressive disease. The Th1/Th2 paradigm of resistance/susceptibility is an oversimplication ofa far more complicated network of regulatory/counter-regulatory interactions and thus a deficit in the understanding of the exact mechanisms involved in resolution vs severity of leishmaniasis. This review, in additionto giving a general overview of basic immunology of Leishmania infection, consolidates findings on immune responses in experimental and human leishmaniasis. Such information is important in giving a feasible direction in designing prophylactic and therapeutic strategies against leishmaniasis.