Human primary dendritic cell subsets differ in their IL-12 release in response to Leishmania major infection

Immunity against leishmaniasis has primarily been studied in experimental infections of mice. It was shown that infected skin dendritic cells (DC) are critical for the induction of protection against this pathogen, and targeting skin DC in vaccination approaches in mice has proven to be successful. However, little is known about the contribution of human DC subsets from the skin to primary immunity against this pathogen. In this study, we have analysed the interaction between different human DC subsets and Leishmania major. Primary human myeloid and monocyte-derived DC ingested the parasite comparable to that of murine skin DC, and this resulted in DC activation and IL-12 release, a cytokine essential for the induction of Th1/Tc1-dependent protection. Interestingly, both Langerhans cells and plasmacytoid DC did not appear to contribute to protection in humans. Thus, in leishmaniasis, both murine and human data suggest that dermal inflammatory DC appear to be superior in promoting protection.