The battle between Leishmania and the host immune system at a glance

Leishmaniasis is a neglected parasitic disease whose diverse clinical manifestations are dependent on the interrelations between intrinsic and extrinsic factors. The infecting species of Leishmania, the parasite’s ability to evade mammal immune response and the host genetic background seems to pre-determine the degree of resistance and sensitivity to infection, regulating the disease outcome. The introduction of metacyclic promastigotes into the dermis of the mammal host by the sand fly originates an unspecific immune response that can difficult the parasite replication and dispersion or, by the contrary favor the
selection of fit parasites, assuring the parasite survival and the disease onset. This review aims to provide a comprehensive outline of the immune response displayed against Leishmania parasites by the host and the strategies
exhibited by the parasite to subvert the host immune mechanisms. Emphasis is given to the early contact of the parasite with the immune system of the host, as this is a crucial time-point for parasite control that might be explored for the development of new and more efficient control measures. The role of neutrophils, macrophages and dendritic cells when facing different species of Leishmania are examined as well as the link of immediate innate immune response with the late acquired immunity.