EFFICIENT AND SUSTAINED GENE-EXPRESSION IN PRIMARY T-LYMPHOCYTES AND PRIMARY AND CULTURED TUMOR-CELLS MEDIATED BY ADENOASSOCIATED VIRUS PLASMID DNA COMPLEXED TO CATIONIC LIPOSOMES

We have used cationic liposomes to facilitate adeno-associated virus ( AAV) plasmid transfections of primary and cultured cell types. AAV pla smid DNA complexed with liposomes showed levels of expression several fold higher than those of complexes with standard plasmids. In additio n, long-term expression (>30 days) of the gene, unlike the transient e xpression demonstrated by typical liposome-mediated transfection with standard plasmids, was observed. Southern analysis of chromosomal DNA further substantiated the hypothesis that the long-term expression was due to the presence of the transgene in the AAV plasmid-transfected g roup and not in the standard plasmid-transfected group. AAV plasmid-li posome complexes induced levels of transgene expression comparable to those obtained by recombinant AAV transduction. Primary breast, ovaria n, and lung tumor cells were transfectable with the AAV plasmid DNA-li posome complexes. Transfected primary and cultured tumor cells were ab le to express transgene product even after lethal irradiation. High-le vel gene expression was also observed in freshly isolated CD3+, CD4+, and CD8+ T cells from normal human peripheral blood. Transfection effi ciency ranged from 10 to 50% as assessed by intracellular interleukin- 2 levels in interleukin-2-transfected cells. The ability to express tr ansgenes in primary tumor and lymphoid cells may be applied toward tum or vaccine studies and protocols which may eventually permit highly sp ecific modulation of the cellular immune response in cancer and AIDS.