Immunofluorescent Staining: BALB/c splenocytes were double-stained with Rat anti-Mouse CD90.2-FITC and Rat anti-Mouse CD19-PE. Small lymphocytes were then gated and analyzed on a FACScan (TM) flowcytometer (BDIS, San Jose, CA). Amount Used: 0.3 ug/10e6 cells.