Augmentation of host defense against Listeria monocytogenes infection by oral administration with polysaccharide RBS (RON)

Immunopotentiating activity of nigerooligosaccharides for the T helper 1-like immune response in mice

The immunopotentiating activity of nigerooligosaccharides (NOS), a mixture of nigerose, nigerosyl glucose and nigerosyl maltose, was studied in vitro and in vivo in mice. Mitogen-induced proliferation of splenocytes from normal mice was augmented in a dose-dependent manner by nigerose of NOS. NOS enhanced interleukin 12 (IL-12) and interferon-gamma (IFN-gamma) production by normal splenocytes in the presence of the potent IL-12 inducer, heat-killed Lactobacillus plantarum L-137, in vitro. Consistent with the in vitro finding, L. plantarum L-137-induced IL-12 production and IL-2-induced IFN-gamma production were augmented in mice fed with a 14.6% NOS diet for 2 weeks compared with mice fed with a control diet. Notably, mice fed with the NOS diet showed significantly longer survival time than the control mice after the induction of an endogenous infection by administering 5-fluorouracil in a lethal dose. Taken together, these results suggest that NOS may exert immunopotentiating activity through the activation of an IL-12-dependent T helper 1-like immune response.

Analysis of effector T cells against the murine syngeneic tumor MethA in mice orally administered antitumor polysaccharide SPR-901

The growth of MethA tumor was significantly inhibited by oral administration of the alpha-glucan SPR-901 in BALB/c (+/+) mice but not in nude mice. Mice treated orally with SPR-901 exhibited an augmentation of antigen-specific resistance against rechallenge with the tumor cells. The tumor-neutralizing activity of regional lymph node cells from MethA-bearing mice against the tumor was augmented by oral administration of SPR-901. The tumor-neutralizing activity of lymph node cells from SPR-901-treated mice mainly appeared in Lyt2+ cells. Furthermore, lymphokine-activated killer activity of these cells was enhanced by administration of SPR-901. The antitumor effect of SPR-901 was abrogated in mice depleted of either L3T4+ or Lyt2+ cells, and in cyclosporin-A-treated mice. These results suggest that Lyt2+ cells are important effector cells in MethA-bearing mice orally administered SPR-901 and that functional exertion of both Lyt2+ and L3T4+ T cells is necessary for the antitumor effect of orally administered SPR-901 in vivo.

Effect of antitumor polysaccharide SPR-901 on antitumor activity in combination with 5-FU

We have examined the effects of the antitumor polysaccharide SPR-901 in combination with 5-fluorouracil (5-FU) on the antitumor activities against mouse syngeneic tumors. SPR-901 was administered p.o. from day 1 to day 10 at the dose rate of 30 mg/kg, and 5-FU was injected i.p. from day 1 to day 5 at the dose rate of 20 mg/kg after BALB/c mice were injected s.c. with 6 x 10(4) cells/mouse of Meth A on day 0. Tumor sizes of mice treated with both SPR-901 and 5-FU were significantly smaller than those from the untreated control group on days 10, 15 and 20. LAK activity of spleen cells from mice treated with both SPR-901 and 5-FU was higher than that from the untreated control group and either the SPR-901 or 5-FU treated group. Flow cytometrical analysis revealed that spleen cells from mice treated with both SPR-901 and 5-FU were much more abundant in both T-cell receptor alpha/beta+ and IL-2 receptor alpha+ T-cells. Furthermore, spleen cells from both the SPR-901- and 5-FU-treated groups exhibited higher growth responses to IL-2 than that from the untreated control group and either of the SPR-901- or 5-FU-treated groups. Therefore, the effects of the antitumor polysaccharide SPR-901 used in combination with 5-FU were augmented as compared with single drug use.

Induction of interleukin 2-responsiveness in thymocytes of the transgenic mice carrying lck-transgene

The role of lck gene in T cell proliferation and differentiation was investigated with transgenic mice carrying human lck cDNA whose expression was regulated by the promoter of mouse H-2Kb and the enhancer element of mouse IgH. RNase protection assay revealed that the lck transgene was expressed in the thymus and spleen, whereas immunoblot analysis demonstrated that amounts of p56lck in freshly isolated lymphoid organs were almost equal between transgenic mice and negative littermates. Cell-surface marker analyses of the thymocytes and peripheral lymphocytes revealed no remarkable difference between both groups. Notable finding is that the thymocytes from transgenic mice showed a significant proliferative response to the stimulation with IL-2, but not the thymocytes from negative littermates. Further analysis revealed that CD4+8- single positive thymocytes proliferated in response to IL-2. While surface expression levels of IL-2R alpha and IL-2R beta of these CD4+8- thymocytes from transgenic and control mice were almost equal before stimulation with IL-2, the expression of IL-2R beta was induced only in transgenic thymocytes after stimulation with IL-2. Immunoblot analysis demonstrated that the expression of p56lck of transgenic thymocytes was not down-regulated at 4 hr after stimulation with IL-2, whereas p56lck of control ones were not detectable any more at 4 hr after stimulation with IL-2. Moreover, in vitro kinase assay substantiated such unchanged expression of p56lck in the thymocytes from transgenic mice: the kinase activities of p56lck did not decrease in thymocytes from transgenic mice after stimulation with IL-2, while kinase activities of control ones were significantly down-regulated by stimulation of IL-2. These results suggested that a significant proliferative response found in the thymocytes from lck-transgenic mice after the stimulation with IL-2 was caused by a constitutive expression of p56lck in these thymocytes even after the stimulation. Our findings, therefore, support a possibility that p56lck may play a role in the IL-2R-mediated signaling system in CD4+8- thymocytes.

Enhancement of murine alveolar macrophage functions by orally administered beta-glucan

The effect of orally administered SSG, a beta-1,3-glucan obtained from the culture filtrate of the fungus Sclerotinia sclerotiorum IFO 9395, on alveolar macrophage (AM) functions of CDF1 mice was examined. SSG administered orally (20, 40, 80 or 160 mg/kg) for 10 consecutive days enhanced the lysosomal enzyme activity of AM. The greatest enhancing effect was observed at 80 mg/kg of SSG. Multiple oral administrations of SSG (10 consecutive days) were needed to induce significant enhancing effects. Phagocytic activity and interleukin-1 (IL-1) production of AM were also augmented by oral administration of SSG, and the kinetics of the activated state differed depending on the kind of activity. However, H2O2 production of AM was not affected by SSG. Orally administered SSG also (40 or 80 mg/kg, 10 consecutive days) increased the number of AM and the greatest increment was observed 14 days after the first administration. On the other hand, the supernatant of Peyer's patch (PP) cells from mice administered SSG (80 mg/kg) orally stimulated the lysosomal enzyme activity of AM in vitro, and enhanced colony stimulating activity (CSA) was detected from this supernatant. These results demonstrate that SSG given by the oral route can activate murine AM both qualitatively and quantitatively, and it would mediated, at least in part, by the activation of PP cells in the intestine.

Protective effect of SPR-901 (RBS) on the decrease of peripheral leukocyte number in 5-fluorouracil-treated mice

5-Fluorouracil (5-FU) induces a decrease in the number of peripheral leukocytes (leukopenia), which is one of the major obstacles in the chemotherapy of cancer. The number of peripheral leukocytes decreased by day 4 in mice injected i.p. with 130 mg/kg of 5-FU and recovered to the normal level by day 8. Such a decrease by 5-FU was prevented to some extent by the oral administration of 30 mg/kg/day of SPR-901. Proliferative responses of bone marrow cells to granulocyte/macrophage colony stimulating factor (GM-CSF) or granulocyte colony stimulating factor (G-CSF) were suppressed by 5-FU treatment and their recoveries were enhanced by SPR-901. The serum level of IL-6 in 5-FU-treated mice was increased by SPR-901. All of the mice treated with 300 mg/kg of 5-FU in combination with SPR-901 survived over 15 days, however, only 4 of 10 mice treated only with 300 mg/kg of 5-FU survived. These results suggest that SPR-901 acts on macrophages directly or indirectly, giving rise to the enhanced production of IL-1, IL-6, and other factors. Some of the factors derived from SPR-901 activated macrophages, perhaps mainly IL-6, act on the early stage of development of multipotent bone marrow progenitors synergistically with GM-CSF.

Augmentation of mitogen-induced interleukin 2 production by oral administration of polysaccharide SPR-901

The effects of oral administration of antitumor polysaccharide SPR-901 (RBS), an alpha-1,3 branched alpha-1,6 glucan, on concanavalin A (Con A)-induced interleukin 2 (IL-2) production of splenocytes were studied. The augmentation effect on Con A-induced IL-2 production was evident when more than 30 mg/kg of SPR-901 was administered orally to mice. On the other hand, oral administration of B512 dextran, an analogous alpha-1,6 glucan, did not show any augmentation effects on IL-2 production. The augmentation effect of SPR-901 on IL-2 production seemed to be mediated mainly by macrophages stimulated with SPR-901.