Figure 6.

Adoptive transfer of murine DCs incubated with R. rickettsii and treated with A. sculptum saliva or PGE₂ does not change IFN-γ or IL-4 recall response of spleen cells following antigenic restimulation in vitro. Bone marrow cells from C3H/HePas mice were differentiated into DCs, seeded at 10⁶ cells/well in 24-well plates and preincubated for 1 h with medium only, A. sculptum saliva collected by pilocarpine stimulation from female ticks fed on host for 7–9 days (1:50 dilution) or PGE₂ (100 nM). Cells were incubated with R. rickettsii (10⁷ bacteria) during 18 h, collected and washed to remove unbound bacteria. Mice were injected subcutaneously with 10⁶ DCs of each group in a 100 μL volume. During the first 5 days after DC transfer, animals of each group received a subcutaneous treatment (100 μL at the same site of DC inoculation) as follows: PBS, A. sculptum saliva (1:50 dilution) and PGE₂ (100 nM). After 30 days of DC transference, the spleen was collected and the cells were restimulated with medium or HKRr for 72 h. The levels of IFN-γ (A) and IL-4 (B) were evaluated in cell-free supernatant of cultures by ELISA. The IFN-γ/IL-4 ratio is also presented (C). Results are expressed as the mean ± SEM. ^*p ≤ 0.05 vs. “DC + R. rickettsii/PBS” group.