Stimulation of in vitro proliferation of murine lymphocytes by synthetic oligodeoxynucleotides.

To elucidate the properties of mitogenic nucleic acids, the ability of oligodeoxynucleotides to stimulate the in vitro proliferation of murine lymphocytes was investigated. The compounds tested were a series of oligodeoxynucleotides, synthesized with either phosphodiester or phosphorothioate chemistry and containing (dG) and (dC) alone or together. Among oligodeoxynucleotides tested, phosphorothioates were more active than phosphodiesters and stimulated thymidine incorporation under the same conditions as mitogenic non-mammalian DNA. Mitogenesis was unaffected by depletion of T cells, suggesting B cells as the predominant cell type stimulated. These results indicate that mitogenic nucleic acids need not have an extended polymeric structure and raise the possibility that antisense compounds have immunologic activity, at least in animal models.