LTA induces TLR2-dependent down-modulation of CCR1, CCR2, and CCR5 from the surface of monocytes. Monocytes (A-B), macrophages, or T-cell blasts (C) derived from human peripheral blood mononuclear cells were incubated in BM alone or treated either with the indicated chemokine at 100nM and 10 μg/mL LTA (A,C) or with increasing concentration of LTA (B) for 1 hour at 37°C, before samples were immunolabeled for cell-surface CCR1, CCR2, and/or CCR5. Results are expressed as the percentage of down-modulation relative to cells in medium alone, and graphs represent the average values from 7 (A), 3 (B), or N (C) independent triplicate experiments. (D) The surface expression level for TLR2 on the different cell types was assessed by flow cytometry. (E) Monocytes were incubated for 1 hour at 37°C with 10 μg/mL LTA (■) or LPS (▩) or pretreated with LPS before adding LTA (□), and samples were stained for cell-surface CCR1, CCR2, and CCR5; (n = 2); *P < .05, **P < .01, and ***P < .005.