THE EFFECT OF TRANSFORMING GROWTH FACTOR-BETA(2)-SPECIFIC PHOSPHOROTHIOATE-ANTI-SENSE OLIGODEOXYNUCLEOTIDES IN REVERSING CELLULAR IMMUNOSUPPRESSION IN MALIGNANT GLIOMA

This in vitro study was aimed at restitution of transforming growth fa ctor (TGF)-beta2-mediated suppression of T-lymphocyte activation withi n malignant gliomas. In early-passage tumor cell cultures of two gliob lastomas (HTZ-153 and HTZ-209) and one malignant astrocytoma classifie d as World Health Organization Grade III (HTZ-243), autologous periphe ral blood mononuclear cells were activated by interleukin-1alpha and i nterleukin-2 in vitro (lymphokine-actived killer cells) and tested for cytotoxic and proliferative activity. In expression studies (Western blot and Northern hybridization) of all three tumors, TGF-beta could b e detected at the protein and messenger ribonucleic acid (mRNA) levels . A polyclonal anti-TGF-beta neutralizing antibody did not enhance lym phocyte proliferation upon stimulation with tumor targets (H-3-thymidi ne incorporation) and slightly stimulated lymphocyte cytotoxicity agai nst autologous target cells. Preincubation of target cells for 12 hour s with TGF-beta2-specific phosphorothioate-anti-sense oligodeoxynucleo tides (S-ODN's) did. however, enhance lymphocyte proliferation up to 2 .5-fold and autologous tumor cytotoxicity up to 60%, compared to contr ols not treated with S-ODN's. Incubation of tumor cells with TGF-beta2 -specific S-ODN's resulted in decreased TGF-beta-specific immunoreacti vity in cultured glioma cells, in reduced TGF-beta2 protein concentrat ion (Western blot), and in a change in the expression pattern of TGF-b eta2 mRNA's. These observations may have implications for in vivo and in vitro activation of a cellular immune response against autologous m alignant glioma cells.