Figure 1.

Parasitemia, CD4⁺ and CD8⁺ T cells, and trypanosome accumulation in the brain parenchyma of infected wild-type (WT) and Myd88^−/− mice. A, Levels of parasitemia. Each point represents the mean log₁₀ parasites per milliliter ± standard error of measurement (SEM) obtained from 9 or 10 animals per group. ^**P < .01 (analysis of variance; significant differences compared with infected WT animals). B, E, H, Mean numbers (± SEM) of CD4⁺ (B), CD8⁺ T cells (E), and Trypanosoma brucei brucei (H) per mm² in the cortex, corpus callosum (C. callosum), and septal nuclei of mice at 30 days post infection (4 animals per group). *P < .05, **P < .01 (unpaired t test; significant differences compared with WT mice at same postinfection time point). C–D, F–G, I–J, Immunofluorescence images from the corpus callosum of mice at 30 days post infection (red, CD4⁺ [C, D] and CD8⁺ [F, G] cells and T. brucei brucei [I, J]; green, cerebral endothelial cells). In WT mice, CD4⁺ (C) and CD8⁺ (F) T cells, and parasites (I) are observed in the parenchyma. Note decreased CD4⁺ and CD8⁺ T-cell accumulation and increased trypanosome density in the brain parenchyma of Myd88^−/− compared with WT mice (D, G, J) (scale bar, 50 μm).