Thionin as an antineoplastic and immunostimulant

Pyrularia Pyrularia The invention involves cellular and biological responses to relatively low concentrations of thionin (such as thionin), which responses are distinct from the direct cytotoxic effect of high concentrations of thionins on cells. These two separate biological responses of immune cells to thionins are related to the presence of two separate and distinct binding sites on the immune cell, a high affinity binding site that reacts with thionins at low concentrations to stimulate the immune cell to provide antitumor protection, and a low affinity site that is responsible for the direct toxicity of thionins to cells. This invention provides, in certain embodiments, methods for using a thionin, either alone or in combination with an interleukin, for stimulation of the immune system. Particular embodiments provide methods for inhibition of tumor formation and/or tumor metastasis, methods for the stimulation of natural killer cells, methods for the stimulation of T cell lymphocyte differentiation and proliferation, and/or methods for the stimulation of cytokine production by various immune cells. Also provided are compositions that include thionin, e.g., thionin, for the treatment and/or prevention of neoplasia, for the treatment of viral infection, for the treatment of immune deficiency (e.g., such as is caused by disease or advancing age). Other embodiments of the invention provide biologically active compounds conjugated or otherwise complexed to the very stable thionin molecule (such as a βME-thionin conjugate), and methods of use of such compounds and/or conjugates for immunostimulation.