P. chabaudi-infected erythrocytes inhibit the LPS and CD40L-induced maturation of DCs. DCs were cultured with infected (pRBC) or uninfected (RBC) erythrocytes for 24 h, as described in Figure 2, then treated with 1 μg/ml of LPS for a further 18 h. (a-f) Results were analyzed as described in Figure 2 (*p ≤ 0.05 pRBC versus RBC). (g,h) DCs (1 × 106) were cultured with 1 × 108 infected erythrocytes (pRBC) before stimulation with CD40L-expressing fibroblasts (filled bars) or control fibroblasts (open bars) at a 1:1 ratio of fibroblasts:DCs. Untreated DCs (Con) and uninfected erythrocyte-treated DCs (RBC) were used as controls. DCs were incubated with fibroblasts for a further 18 h before analyzing CD40 expression and cytokine production. CD40 expression on DCs is shown as the mean fluorescent intensity on CD11c+ cells. IL-12 production is shown as the mean optical density (OD) read at 450 nm. Results show the mean value ± s.e. of triplicate samples per group (*p ≤ 0.05 pRBC versus RBC).