Cells from BALB/c mesenteric lymph nodes were double-stained with Cd19 monoclonal antibody, clone 6D5 (FITC) (Cat # MAB5687) and Cd3e monoclonal antibody, clone C363.29B (PE) (Cat # MAB6102), gated on small lymphocytes and analyzed on a FACScan™ flow cytometer (BDIS, San Jose, CA).