Increased numbers of CD11b^highLy6C⁺ monocytes in the spleen during the first 20 days of acute P chabaudi infection. (A) Spleen cells from uninfected and day 8–infected C57Bl/6 mice were stained with antibodies against CD11c, CD8, Ly6C, CD11b, CD19, CD3, Ter119, as well as 7AAD. (Left) Gating strategy was a FACS plot of CD19, CD3, Ter119, 7AAD, and forward scatter (FSC) on spleen cells. Gate was set on viable lineage-negative cells as well as side scatter (SSC) and FSC. (Right) FACS plot showing CD11b and Ly6C profiles of gated cells. (B) Histogram of gated CD11b^highLy6C⁺ cells from day 8–infected cells: (left) F4/80, (middle) CD8, and (right) CD11c. Shaded histogram shows unstained control. Numbers show the percentage of positive cells within the region. (C left) Dot plot of CD11b and CD11c on day 8–infected spleen cells gated on FSC and SSC. Histograms of class II, CD86, and CD40 on gated CD11c^high cells (shown in left panel) and CD11b^highLy6C⁺ cells gated as described in panel A. Each experiment was performed with at least 3 mice per time point and repeated 3 times. (D) Total numbers of CD11b^highLy6C⁺CD11c ^low monocytes (left y-axis) in the spleen of C57Bl/6 mice during the first 20 days of a primary intraperitoneal infection with P chabaudi and percentage of parasitemia (right y-axis). Error bars represent SEM of the values from 3 individual mice. Each experiment was performed with at least 3 mice per time point and repeated 3 times. Significant differences were determined using the Student t test.