Are neutrophils important host cells for Leishmania parasites?

Neutrophils are the most crucial cells for early defence against infections. When appropriately activated, they can kill obligate intracellular pathogens such as Leishmania. However, once the phagocytotic killing has been evaded, neutrophils can serve as host cells for Leishmania. Parasitized neutrophils were suggested to function as a 'Trojan horse', to transfer Leishmania silently to macrophages. In vivo imaging has contributed a second evasion mechanism. We termed it the 'Trojan rabbit' strategy, whereby parasites escape dying neutrophils to infect macrophages. Here, we discuss the different experimental models used to study neutrophil function in leishmaniasis. We suggest that the capacity of neutrophils to function as an immune evasion target depends on the genetic background of the host and the parasite strain used for the experiments.