The molecular mechanisms that control CD8(+) T cell proliferation and differentiations are poorly understood. Consequently, better understanding of the molecular pathways that regulate these processes may have an impact on the numbers and efficiency of antigen-specific cells that can be generated for cellular immunotherapy applications. Using differential display, we previously determined that alpha nascent polypeptide associated complex (alpha NAC) was identified as a potential target as its protein expression was found to be down-regulated as differentiation progressed in cultured human CD8(+) T cells. Here anti-sense technology was used to further investigate the role which alpha NAC may play in proliferation and differentiation. Human purified CD8(+) T cells were cultured in the presence of sense, non-sense and anti-sense oligonucleotides against the mRNA of alpha NAC. We reported that in the presence of anti-sense oligonucleotides expanded CD8(+) T cells exhibited higher levels of differentiation and activation markers and also increased proliferation response compared to cells cultured with sense-oligonucleotides. Furthermore, the functional cytotoxicity of CD8(+) T cells cultured with anti-sense was increased to 66% (+/-4.7%) compared to 42% (+/-3.2%) in cells expanded in the presence of oligonucleotides controls. Taken together, our results demonstrated that inhibition of alpha NAC protein induced not only cell proliferation but also differentiation and cytotoxic activity of CD8(+) T cells.