ANXA5 and infection: However, independent of the source of the B lymphocytes (secondary lymphatic tissue or PBMC) or their isolation procedure (FACS sorting or their “untouched” isolation by using magnetic bead-coupled depleting antibodies directed against surface antigens that B cells lack), we always noticed a considerable loss of viable cells during the first 3 days of infection accompanied by a varied but generally high fraction of annexin V binding cells.