Evaluation of Selected Immunomodulatory Glycoproteins as an Adjunct to Cancer Immunotherapy.

Polysaccharopeptide (PSP), from Coriolus versicolor, has been used widely as an adjuvant to chemotherapy with demonstrated anti-tumor and broad immunomodulating effects. While PSP's mechanism of action still remains unknown, its enhanced immunomodulatory potential with acacia gum is of great interest. Acacia gum, which also contains polysaccharides and glycoproteins, has been demonstrated to be immunopotentiating. To elucidate whether PSP directly activates T-cell-dependent B-cell responses in vivo, we used a well-established hapten carrier system (Nitrophenyl-chicken gamma globulin (NP-CGG)). 6-week C57BL/6 male mice were immunised with 50 µg of NP25-CGG alum precipitate intraperitoneally. Mice were gavaged daily with 50 mg/kg PSP in a vehicle containing acacia gum and sacrificed at days 0, 4, 7, 10, 14 and 21. ELISA was used to measure the total and relative hapten-specific anti-NP IgA, IgM and IgG titre levels compared to the controls. It was found that PSP, combined with acacia gum, significantly increased total IgG titre levels at day 4 (P< 0.05), decreased IgM titre levels at days 4 and 21 (P< 0.05) with no alterations observed in the IgA or IgE titre levels at any of the time points measured. Our results suggest that while PSP combined with acacia gum appears to exert weak immunological effects through specific T-cell dependent B-cell responses, they are likely to be broad and non-specific which supports the current literature on PSP. We report for the first time the application of a well-established hapten-carrier system that can be used to characterise and delineate specific T-cell dependent B-cell responses of potential immunomodulatory glycoprotein-based herbal medicines combinations in vivo.

PSP activates monocytes in resting human peripheral blood mononuclear cells: immunomodulatory implications for cancer treatment.

Polysaccharopeptide (PSP), from Coriolus versicolor, has been used as an adjuvant to chemotherapy, and has demonstrated anti-tumor and immunomodulating effects. However its mechanism remains unknown. To elucidate how PSP affects immune populations, we compared PSP treatments both with and without prior incubation in phytohaemagglutinin (PHA) - a process commonly used in immune population experimentation. We first standardised a capillary electrophoresis fingerprinting technique for PSP identification and characterisation. We then established the proliferative capability of PSP on various immune populations in peripheral blood mononuclear cells, using flow cytometry, without prior PHA treatment. It was found that PSP significantly increased the number of monocytes (CD14(+)/CD16(-)) compared to controls without PHA. This increase in monocytes was confirmed using another antibody panel of CD14 and MHCII. In contrast, proliferations of T-cells, NK, and B-cells were not significantly changed by PSP. Thus, stimulating monocyte/macrophage function with PSP could be an effective therapeutic intervention in targeting tumors.

High-throughput screening platform for anticancer therapeutic drug cytotoxicity.

There are substances that kill cancer cells, but induce T cell proliferation, like thalidomide. To find more of these, a new anticancer drug screening strategy is vital. In this study we report the development of a differential cytotoxicity screening or evaluation platform using the CellTiter-Glo (Promega, Annandale, NSW, Australia) luminescent cell viability assay (ATP assay) and also the CellTiter 96 AQueous (Promega) one solution cell proliferation assay [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay]. The results suggested the platform consisting of the combination of the ATP assay be used for quantifying peripheral blood mononuclear cells, while the more economic MTS colorimetric assay is well suited to be used detecting cell viability of cancer cells. In addition, we found paclitaxel (Taxol, MP Biomedicals Australasia Pty Ltd., Seven Hills, NSW, Australia) to be a useful control for this routine screening methodology. Taxol exhibits the desirable in vitro feature of differential cytotoxicity that spares the immunological cells, when used at a concentration that will kill the majority of the cancer cell population.