Immunofluorescent Staining: Cells from BALB/c mesenteric lymph nodes were double-stained with anti-Mouse CD3e-FITC and anti-Mouse CD45R/B220-R-PE (clone RA3-6B2), gated on small lymphocytes and analyzed using a FACScan (TM) flow cytometer (BDIS, San Jose, CA). Amount used: < / = 3 ug/10e6.