CpG-A and IL-15 in combination significantly enhances activation of T cells from healthy volunteers but not T cells of patients. PBMCs from SS patients (n = 11, ▪) and healthy volunteers (n = 7, ▦) were stimulated with CpG-A, control CpG ODN, IL-15, or the combination of CpG-A and IL-15 as described in Figure 2. Cells were then harvested, stained with appropriate antibodies, and analyzed for the expression of CD69 on CD8 (A) and CD4 (B) T cells. Data represent means (± SD) of tested individuals and are presented as a percentage of CD8 or CD4 T cells expressing CD69. ^*P < .05 compared with IL-15 or CpG-A.