Anti-tumor effect and mechanism of SEA-Fab' coupled protein on gastric tumor.

The anti-tumor effect and mechanism of SEA-Fab' coupled protein on gastric tumor was studied. The target cell Walker-256 was treated with SEA-Fab' synthesized chemically or SEA respectively for 24 h, 36 h or 72 h. PBMC+Walke-256 cells served as controls. The apoptotic index of SEA-Fab' against effector cells was detected. In the mouse gastric cancer models (n = 60), SEA-Fab', SEA and normal saline was injected in experimental group, SEA group and control group respectively. The occurrence and weight of tumor was observed. The results showed that the apoptotic index was significantly higher in the SEA-Fab' (34.6%-68.9%) and SEA group (15.5% -31.9%) than in PBMC+Walker-256 group (5.5%-12.8%) with the difference being significant (P < 0.01). And there was significant difference between SEA-Fab' group and SEA group (P < 0.01). The tumor weight in SEA-Fab', SEA and control groups was 3.64 +/- 0.53 g, 0.78 +/- 0.26 g and 0.49 +/- 0.17 g respectively with the difference being statistically significant between the SEA-Fab' group, SEA group and the control group (P < 0.01). In the SEA-Fab's and SEA groups, there were CD4+ T and CD8+ T cell infiltrates, but in the cotnrol group, no or few T lymphocytes were seen in the mouse tumor tissue. It was concluded that SEA-Fab' was more effective to activate T lymphocytes to kill the tumor cells than SEA used alone. It was feasibility by using the monoclonal antibody as carrier to perform the targeted immunotherapy of gatric tumor.