Transforming Growth Factor-β-Mediated Regulation of Human Peripheral Blood Mononuclear Cell Proliferation as Detected with Phosphorothioate Antisense Oligodeoxynucleotides

Transforming growth factor-β (TGF-β) is a potent cytokine that has influence upon immunosuppressive as well as proinflammatory processes. In this context we have investigated the role of endogenous TGF-β in human peripheral blood mononuclear cells (PBMCs) by TGF-β1 phosphorothioate antisense oligodeoxynocleotides (TGF-β1-S-ODNs). In short-term cultures (up to 3 days), TGF-β1-S-ODNs-treated, interleukin 2-activated PBMCs displayed a growth advantage (up to 148%) compared to nonsense or untreated controls as measured by cell counting and [3H]thymidine incorporation. Long-term antagonization of TGF-β production (up to 12 days) showed no significant differences between both antisense- and nonsense-treated PBMCs. The efficacy and specificity of TGF-β1-S-ODNs effects was validated by gene expression studies (Northern blot and ELISA) and analysis of cellular uptake of BrdU-labeled S-ODN (Immunocytochemistry). TGF-β1S-ODNs at the final concentration of 1 μM reduced TGF-β1 protein concentration up to 65% in PBMCs cultures without significant changes in TGF-β1 mRNA expression. These experiments demonstrate that TGF-β1S-ODNs specifically antagonize TGF-β1-mediated autocrine suppression of IL-2-dependent PBMC activation. TGF-β1-specific antisense oligonucleotides may represent a promising immunoresponse modifying agent that could be used for T-cell directed immunostimulation.