CEACAM5 and neoplasm: Notably, the pre-incubation with the autologous CD19+ healthy B cells, but not with T cells from the same donor and in same numbers, significantly improved the subsequent killing of the CD19+ tumor cells (Figure 1A), whereas the killing of the CEA+ colorectal cancer cells by the CEA-CAR T cells for comparison, was unaffected (Figure 1B).