Preparation of murine B7.1-glycosylphosphatidylinositol and transmembrane-anchored staphylococcal enterotoxin. A dual-anchored tumor cell vaccine and its antitumor effect

BACKGROUND: The authors have previously reported a tumor cell vaccine modified with superantigen staphylococcal enterotoxin A (SEA) and its antitumor effect. The tumor cell vaccines modified with multiple immune activators frequently elicited stronger immune responses against established tumors than single-modified vaccines. METHODS: The authors explored the effectiveness of a tumor cell vaccine transduced with immune activators, dual-modified using the protein transfer technique. First, a glycosylphosphatidylinositol (GPI)-anchored murine B7.1 (mB7.1-GPI) and a transmembrane-anchored SEA (TM-SEA) were genetically generated. Then, the murine lymphoma EL4 cells were dual modified with the incorporation of mB7.1-GPI and TM-SEA onto the cell surface. Flow cytometry and laser confocal microscopy showed that the incorporation of B7.1 and SEA molecules onto EL4 cells was quite stable. RESULTS: The dual-modified tumor cell vaccine EL4/mB7.1-GPI + TM-SEA elicited significantly stronger antitumor immune responses both in vitro and in vivo when compared with the single-modified tumor cell vaccines EL4/mB7.1-GPI and EL4/TM-SEA. CONCLUSIONS: The results of the current study validated the novel approach for preparing tumor cell vaccines modified with dual immune active molecules using the protein transfer technique, and supported the feasibility and effectiveness of the dual-modified tumor cell vaccine.