CpG-A and IL-15 synergize in inducing IFN-γ production. PBMCs from SS patients (n = 7, ▪) and healthy volunteers (n = 6, ▦) were stimulated with CpG-A, control CpG ODN, IL-15 (1 ng/mL), or the combination of CpG-A and IL-15 as described in Figure 2. Cytokine levels were measured in cell-free supernatants by ELISA. Data represent means (± SD) of tested individuals. ^*P < .05 compared with CpG-A or IL-15 alone.