The biological activity and immunotherapeutic properties of AS-101, a synthetic organotellurium compound.

AS-101 (ammonium trichloro[dioxoethylene-O,O'-]tellurate) is a newly developed synthetic compound with immunomodulating properties and minimal toxicity. We evaluated the effects of AS-101 on various parameters of the activation and function of immunocompetent cells. AS-101 induced IL-2 receptor expression, IL-2 production and proliferation by human and mouse lymphocytes in vitro and enhanced the production colony-stimulating factor (CSF) by mouse spleen cells. In vivo treatment of Balb/c mice with AS-101 caused a significantly increased production of IL-2 and CSF in vitro in the presence of mitogen. When administered systemically to mice, AS-101 mediated antitumor effects in vivo. These results suggest that AS-101 is an active biological response modifier, which might have potential use in the treatment of conditions such as malignancy, AIDS and some types of immune deficiency.

A new immunomodulating compound (AS-101) with potential therapeutic application.

There has been interest in the potential of synthetic compounds to modify immune responses by imitation of cytokine action. Direct administration of interleukin 2 (IL-2) in conjunction with adoptive transfer of lymphokine activated killer cells has been used in the treatment of cancer, but there are toxic effects resulting from the high doses of IL-2 required. We have developed a new synthetic compound, ammonium tri-chloro(dioxoethylene-O,O'-)tellurate (AS-101), which has immunomodulating properties and minimal toxicity. The effects of AS-101 on the activation and function of immunocompetent cells have been assessed. We have found that AS-101 induces proliferation and IL-2 production by human lymphocytes in vitro, and enhances the production of IL-2 and colony-stimulating factor by mouse spleen cells. Splenocytes of BALB/c mice injected with AS-101 increased production of IL-2 and CSF in vitro in the presence of mitogen. Mononuclear cells of normal donors acquired responsiveness to recombinant IL-2 and bound monoclonal antibody to IL-2 receptor after incubation with AS-101. Splenocytes of mice treated in vivo with AS-101 expressed high levels of IL-2 receptor. The stimulation of lymphocytes by AS-101 apparently involves an increase in intracellular free calcium. AS-101 administered systemically to mice mediated antitumour effects which could be attributable to its immunomodulatory properties. In addition, AS-101 could directly enhance the ratio of OKT4 to OKT8-positive cells in cultured mononuclear cells from AIDS (acquired immune deficiency syndrome) patients. These results indicate that AS-101 is potentially useful in the treatment of clinical conditions involving immunosuppression.