Free and Liposome-Encapsulated Double-Stranded RNAs as Inducers of Interferon, Interleukin-6, and Cellular Toxicity

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Abstract
Poly(rI:rC) and Ampligen were entrapped in liposomes that were covalently coupled to Protein A, permitting binding to antibodies specific for the major histocompatibility complex-encoded H2K molecule of L929 cells, or to control antibodies. Free and encapsulated polynucleotides were compared for their capacity to stimulate secretion of interferon (IFN) and interleukin-6 (IL-6) and to induce cellular toxicity on L929 cells pretreated with IFN-alpha/beta. Free and encapsulated poly(rI:rC) or Ampligen (poly(rI:rC12-rU] induced similar levels of secretion of IFN over a broad dose range. The activity of the liposome-encapsulated polynucleotides was dependent on its binding to an antibody that permitted cell association and internalization; the same liposomes were inactive in the presence of control antibodies. IL-6 secretion was induced by double-stranded (ds) RNA in a dose-dependent manner, with a significantly greater effect seen for targeted, liposome-encapsulated material. The marked toxicity of targeted poly(rI:rC), as compared to free poly(rI:rC), was confirmed. Encapsulated Ampligen was less toxic than encapsulated Poly(rI:rC).