For each co-culture, CD4CAR or vector control NK-92 effector cells were incubated with tumor cells that were comprised of equal numbers of on-target CD4+ cells, CFSE-stained KARPAS-299 or CFSE-stained CCRF-CEM, and “off-target” CMTMR-stained CD4-, CD5+ MOLT4 acute lymphoblastic leukemia cells [45]. Here, CD5 is linked to acute lymphoblastic leukemia.