Augmented TLR9 expression correlates with increased responsiveness to CpG DNA. (A) Resting B lymphocytes were seeded in a 96-well plate (1 × 10⁹ cells/L) in complete RPMI. Cells were incubated in medium or prestimulated with anti-μ (10.5 μg/mL) for 12 hours. Cells were then stimulated for a further 48 hours with the indicated concentrations of CpG DNA (2006). Proliferation was determined by measuring the uptake of [³H]-thymidine (0.5 μCi/well [0.0185 MBq/well]) into the cells. Control cells were incubated in medium alone for the duration of the experiment. Results are expressed as cpm × 10³ ± SEM and are representative of 3 independent experiments. (B-C) Resting B lymphocytes were seeded in a 24-well plate (1 × 10⁹ cells/L) in complete RPMI. Cells were incubated in medium or prestimulated with anti-μ (10.5 μg/mL) or anti-CD40 (0.5 μg/mL) for 12 hours. Cells were then stimulated for a further 24 hours with CpG DNA (2006; 0.6 μg/mL). Supernatants were removed from cells and analyzed for CCL3 (B) and CCL22 (C) production by ELISA. Results are expressed in pg/mL (mean ± SEM) and are representative of 2 independent experiments.