Parasite burdens were determined at wk 3 (Fig. 4B), and wk 6 and 13 (data not shown). As expected from the lesion data, parasite loads were higher in Lm/CpG-vaccinated IL-17R−/− mice if compared with WT at the early time point. No differences in parasite burdens between the two groups were observed at later time points (data not shown). The analysis of the find more dermal site during the “silent” phase (2 wk) revealed, as expected, that the frequency of CD4+Th17 cells is elevated in the ears of Lm/CpG-vaccinated
WT animals. In contrast, the frequency of these cells was decreased fourfold in IL-17R−/− mice vaccinated with the same vaccine (Fig. 5A). The same trend was observed for IFN-γ expression, with an even more dramatic decrease in frequency of Th1 cells in the IL-17R−/− mice (tenfold). The absolute number of IL-17+ and IFN-γ+ T cells is shown in Fig. 5B, and confirms that Th1 cells are the most decreased population in the deficient mice. The frequency of Treg was increased in Seliciclib purchase IL-17R−/− mice (Supporting Information Fig. 3). A decrease in effector numbers concomitant to an increase in Treg could explain the elevated parasite burdens in the ears of IL-17R−/− mice 2 wk post vaccination. Because IL-17 has been reported to contribute to inflammatory immune response by recruiting neutrophils, which are implicated in the control of leishmaniasis, we wanted to determine
whether decreased frequencies of Th17 cells would result in differences in neutrophil accumulation in the vaccination site. To determine this, we quantified the relative percentage of different cell populations in cytospin preparations generated from the vaccinated ears at wk 2. Figure 5C confirmed that neutrophils frequencies were significantly increased in WT mice vaccinated with Lm/CpG and
decreased in the IL-17R−/− animals. The relative frequencies of mast cells and melanocytes were significantly decreased in the Lm/CpG-vaccinated WT mice, probably a reflexion of the relative higher numbers of neutrophils in the skin of these animals. We also did not detect infected neutrophils, and very few infected macrophages (5%), in the cytospin preparations from Lm/CpG-vaccinated mice. Infected cells were more prominent (5% neutrophils, 21% macrophages) in L. major-infected mice (data not shown). This suggests that the phagocytic ability of these cell types was enhanced Tangeritin by Lm/CpG vaccination. Cytokine levels were also determined in the draining lymph nodes of WT and IL-17R−/− mice at wk 2 post inoculation. IL-6 and TGF-β production, which in conjunction causes Th17 development, was significantly increased in WT mice vaccinated with Lm/CpG (p=0.0001 and p=0.001, Fig. 6A and B), but not in IL-17R−/− animals. IL-17 was only detected in WT mice vaccinated with Lm/CpG (Fig. 6C). IL-12 was secreted by lymph node cells of all mice vaccinated with Lm/CpG (Fig. 6D). Interestingly, IFN-γ could not be detected in IL-17R−/− immunized with this vaccine (Fig. 6F).