Abstract: AIM: To research the antitumoral effect in vitro of the immunotoxin composed by RTA and EGFR mab. METHODS: Taking SPDP as the coupling agent, RTA, which was purified from castor bean, was linked with EGFR mab.After further purification, the purification of RTA and the construction of the immunotoxin were detected by SDS-PAGE.The combining capacity to HepG2 cells was detected by DAB chromogenic method.The immunoreactivity was detected by indirect ELISA.The cytotoxicity in vitro was detected by CCK-8 method. RESULTS: The immunotoxin was constructed successfully.Immunotoxin retained the combining capacity of EGFR mab to HepG2 cells and a major part of the immunoreactivity.The immunotoxin displayed a different cytotoxicity between HepG2 cells and LO2 cells. CONCLUSION: Immunotoxin plays a specific role in suppressing the multiplication of the hepatoma carcinoma cell and has a good prospect in liver cancer treatment.

Key words: ricin A-chain, monoclonal antibody, immunotoxin