<strong>Immunofluorescent Staining:</strong> Cells from BALB/c spleen were double-stained with rat anti-Mouse IgM-PE (Cat#AM08015RP-N or AM08015RP-S) 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: 0.3 ug/10e6 cells.