FIG. 4.
Impaired immune defense against S. pyogenes in macrophage-depleted mice. BALB/c mice were depleted of macrophages by treatment with carrageenan and then challenged intravenously with 105 CFU of S. pyogenes. Control mice were injected with PBS. (A) Flow cytometric analysis of spleen cells isolated from control (left) or carrageenan-treated (right) animals, showing the efficiency of depletion. The dot plot in each upper right quadrant shows the F4/80 and Mac-1 profile for macrophages. (B) Survival curves of macrophage-depleted (□) and control (CTR) (▪) mice. Each group contained 10 mice. (C) Bacteremias of macrophage-depleted (solid bars) and control (open bars) mice 24 and 48 h postinoculation (n = 5 mice/group). (D) Bacterial loads in livers and spleens of macrophage-depleted (solid bars) and control (open bars) mice 48 h postinfection (n = 5 mice/group). (*, P < 0.05). One representative experiment out of four is shown. The error bars indicate standard deviations.