Antisense oligonucleotide represents an interesting tool for selective inhibition of gene expression. However, their low efficiency of introduction within intact cells remains to be overcome. Antisense-$TGF{eta}$ (25 mer) and antisense-$TGF{eta}$ (18 mer) were used to study the cellular transport and biological function of antisense oligonucleotide in vitro. Since TGF and TNF play on important role in regulating the nitric oxide production from macrophages, the action of the above antisense oligonucleotides was easily monitored by the determination of nitrite. Poly-L-lysine, benzalkonium chloride and tetraphenylphosphonium chloride were used as polycations, which neutralize the negative charge of antisense oligonucleotide. The production of nitric oxide mediated by .gamma.-IFN in mouse peritoneal macrophage was increased by antisense-TGF.betha. in a dose-dependent manner. Antisense-$TGF{eta}$ reduced the nitric oxide release from activated RAW 264.7 cells. Significant enhancement in the nitric oxide production was investigated by the cotreatment of poly-L-lysine with antisense-$TGF{eta}$On the meanwhile, inhibition effect of antisense-$TGF{eta}$ is not changed by the addition of poly-L-lysine. These results demonstrate that control of expression of $TGF{eta}$ and TNF.alpha. gene is achieved using antisense technology and the cellular uptake of antisense oligonucleotide could be enhanced by ion-pairing.