Figure 1.

The immunomodulatory role of neutrophils at the site of Leishmania transmission by sand fly bite. Metacyclic promastigotes deposited in the skin by infected sand flies are taken up primarily by neutrophils that are rapidly recruited to the site of bite. Infected neutrophils recovered from the ear dermis have accelerated expression of apoptotic markers, with the majority dying in situ to release viable parasites that may be better adapted for intracellular survival and growth following their uptake by macrophages. The engulfment of infected and uninfected cells or apoptotic bodies by macrophages may inhibit the activation of infected macrophages in the inflammatory site. The initial infection of dermal DCs appears to take place primarily in the context of their capture of parasitized neutrophils. This encounter strongly reduces their priming capacity and consequently delays the immune response against the parasite until the acute neutrophilic response is resolved.