In vitro Stimulation of cytokine release in human PBMCs by REP 9 and REP 9C. Human PBMCs were exposed to no compound, CPG 7909, REP 9, and REP 9C, and levels of secreted cytokines after 48 h of induction were determined as described in the material and methods. Data is depicted on different scales (7, 70, 300, and 20,000 pg/ml) to demonstrate differences in cytokine levels measured. Values plotted are mean +/- standard deviation (n = 3). * = statistically insignificant difference in cytokine concentrations compared to untreated controls, + = statistically significant reduction in cytokine concentrations (REP 9C versus REP 9) (p < 0.05).