Cross-presenting dendritic cells are required for control of Leishmania major infection.

Leishmania major infection induces self-healing cutaneous lesions in C57BL/6 mice. Both IL-12 and IFN-γ are essential for the control of infection. We infected Jun dimerization protein p21SNFT (Batf3(-/-) ) mice (C57BL/6 background) that lack the major IL-12 producing and cross-presenting CD8α(+) and CD103(+) DC subsets. Batf3(-/-) mice displayed enhanced susceptibility with larger lesions and higher parasite burden. Additionally, cells from draining lymph nodes of infected Batf3(-/-) mice secreted less IFN-γ, but more Th2- and Th17-type cytokines, mirrored by increased serum IgE and Leishmania-specific immunoglobulin 1 (Th2 indicating). Importantly, CD8α(+) DCs isolated from lymph nodes of L. major-infected mice induced significantly more IFN-γ secretion by L. major-stimulated immune T cells than CD103(+) DCs. We next developed CD11c-diptheria toxin receptor: Batf3(-/-) mixed bone marrow chimeras to determine when the DCs are important for the control of infection. Mice depleted of Batf-3-dependent DCs from day 17 or wild-type mice depleted of cross-presenting DCs from 17-19 days after infection maintained significantly larger lesions similar to mice whose Batf-3-dependent DCs were depleted from the onset of infection. Thus, we have identified a crucial role for Batf-3-dependent DCs in protection against L. major.