Co-modification of IL-2-TNF alpha fusion gene and B7.1 gene to murine breast tumor cells leads to improved tumor rejection and vaccine effect

To improve the vaccine potency of gene-modified tumor cells. Using recombinant adenoviruses, we expressed the B7.1 gene in murine breast tumor cell line EMF6 and a subline previously transfected with retrovirus vector XdF harboring the IL-2-TNF alpha fusion gene. Immunization/challenge experiments demonstrated that IL-2-TNF alpha/B7.1 co-modified tumor cells possessed a lower tumorigenicity in vivo and an improved tumor-specific vaccine potency compared with single gene transfectant (P < 0.05). Three weeks after immunization with a variety of tumor cells, the mixed lymphocyte and tumor cells reaction assay (MLTB) and 51Cr-release assay were performed to test cellular immunity function. The results indicated that IL-2-TNF alpha and B7.1 together induced a more potent antitumor immune response than either molecule alone, 25% higher than IL-2-TNF alpha and 20% higher than B7.1, respectively. The IL-2-TNF alpha fusion gene and B7.1 gene act in concert to improve their antitumor effectiveness.