Figure 5 Patient's lymphocytes grafted with anti‐carcinoembryonic antigen (CEA) receptor lysed autologous CEA⁺ tumour cells. Lymphocytes from peripheral blood (PBL) of patient No 1 were grafted with the BW431/26‐scFv‐Fc‐ζ receptor (PBL‐439) and coincubated (1.25–10×10⁴ cells/well) with autologous CEA⁺ tumour cells (5×10⁴ cells/well) for 48 hours. Coincubation with PBL without BW431/26‐scFv‐Fc‐ζ receptor served as control. Viability of tumour cells was determined colorimetrically by a tetrazolium salt based XTT assay, as described in materials and methods.