Normal human peripheral blood cells were stimulated with Anti-Human CD3 and Anti-Human CD28 Functional Grade Purifieds (Product # 16-0037-81 and Product # 16-0289-81) for 3 days. Cells were surface stained with Mouse IgG1 K Isotype Control PE-eFluor® 610 (Product # 61-4714-82) (blue histogram) or Anti-Human CD357 (AITR/GITR) PE-eFluor® 610 (purple histogram). Cells in the lymphocyte gate were used for analysis.