Immunofluoscent Staining: Cells from BALB/c spleen were activated by PMA (10 ng/ml) and Ionomycin (400 ng/ml) for 48 hours, then stained with anti-CD25-FITC and analyzed on a FACScan (TM) flow cytometer (BDIS, San Jose, CA). Amount Used: 0.1 ug/10e6 cells.