BLP down-regulates inflammatory chemokine receptor expression. (A) Macrophages (i), neutrophils (ii), CD4⁺ T cells (iii), and dendritic cells (iv) from D6-deficient mice were stimulated with BLP at 50 ng/mL (macrophages, neutrophils, DCs) or 1 μg/mL (T-cells) for 4 hours and inflammatory chemokine receptor expression determined by qPCR. (B) Transcripts for homeostatic chemokine receptors were also determined by qPCR. (C) Untreated or BLP-treated (i) mouse CD4⁺ T cells and (ii) human monocytes were tested for migration toward CCL3 and CCL2, respectively, in transwell assays. The data represent the alterations in the measured migration index and are representative of 3 experiments each. SEMs are indicated for the monocyte migration assays. (Di) Surface CCR2 levels were assessed after treatment of macrophages and DCs for 16 hours with 100 ng/mL BLP by analysis of binding of the Alexa Fluor–labeled CCR2 ligand, CCL2. Binding of this labeled ligand was quantified using flow cytometry. (Dii) BLP does not alter cell surface expression of CCR7 as measured by PE-labeled CCL19 binding and internalization. All bars for qPCR data show mean fold change of 4 replicates ± SEM compared with cells treated with vehicle. Marked bars are statistically different from unstimulated cells (Student t test; *P < .01).