Immunofluorescent Staining: Cells from BALB/c spleen were double-stained with Rat anti-Mouse CD5-R-PE and rat anti-mouse CD19-FITC (Clone 6D5), following which small lymphocytes were gated and analyzed using a FACScan (TM) flow cytometer (BDIS, San Jose, CA). Amount used: < / = 0.2 ug/10e6 cells.