▁from ▁those ▁taken ▁form ▁multiple ▁my el oma ▁or ▁s P CL ▁patients . ▁For ▁example : ▁p P CL ▁pl asma ▁cells ▁more ▁often ▁express ▁CD 2 0 ▁ant igen , ▁which ▁is ▁considered ▁important ▁in ▁anch oring ▁pl asma ▁cells ▁to ▁the ▁b one ▁mar row ▁st rom a , ▁than ▁do ▁those ▁on ▁pl asma ▁cells ▁taken ▁from ▁my el oma ▁patients ▁( 5 0 % ▁vs . ▁ 1 7 % ); ▁p P CL ▁pl asma ▁cells ▁often ▁lack ▁CD 5 6 ▁ant igen ▁which ▁is ▁present ▁on ▁the ▁majority ▁of ▁pl asma ▁cells ▁taken ▁form ▁multiple ▁my el oma ▁patients ; ▁and ▁p P CL ▁pl asma ▁cells ▁more ▁frequently ▁express ▁CD 2 8 ▁than ▁do ▁s P CL ▁pl asma ▁cells . ▁Thus , ▁imm un oph en ot yp ing ▁supports ▁that ▁notion ▁that ▁multiple ▁my el oma , ▁s P CL , ▁and ▁p P CL ▁show ▁crit ically ▁important ▁fundamental ▁differences ▁that ▁may ▁explain ▁their ▁different ▁clin ical ▁present ations , ▁courses , ▁responses ▁to ▁ther apy , ▁and ▁pro gn oses . ▁ ▁Di agn osis ▁The ▁International ▁My el oma ▁Working ▁Group ▁has ▁defined ▁the ▁di agnostic ▁criteria ▁for ▁pl asma ▁cell ▁le uk emia ▁as ▁the ▁presence ▁in ▁blood ▁of ▁> 2 x 1 0 9 ▁pl asma ▁cells ▁per ▁liter ▁or , ▁altern atively , ▁> 2 0 % ▁of ▁nucle ated ▁blood ▁cells ▁being ▁pl asma ▁cells . ▁More ▁recently , ▁the ▁Group ▁has ▁suggested ▁that ▁values ▁of