Effect of beta-glucans on the nitric oxide synthesis by peritoneal macrophage in mice

Nitric oxide (NO) is an important effector molecule on antimicrobial and antitumor effects of macrophages. (1 -> 3)-beta-D-Glucan (beta-glucan) is well known to show various immunopharmacological effects such as antimicrobial effect and antitumor effect by activating various points of host defense mechanisms. This paper deals with NO synthetic activity of peritoneal macrophage (PM) induced by beta-glucan administration in mice. The activity was determined by measuring NO concentration in PM culture by Griess reagent after 24 or 48 h in vitro culture. Administration (i.p. or i.v.) of a branched soluble (1 -> 3)-beta-D-glucan, grifolan (GRN), from Grifola frondosa enhanced NO synthesis of PM dose and time dependently. The activity was abrogated by the addition of N(G)-monomethyl-L-arginine (L-NMMA) in vitro. The most significant activity was observed at 3-7 d after the administration of GRN (250 mu g/mouse). PM from all strains of ICR, C3H/HeN, C3H/HeJ, BALB/c, BALB/c nu/nu, C57BL, and AKR mice showed significant activity by GRN administration. Among beta-glucans tested, SSG and OL-2, highly branched soluble glucans, and a particulate beta-glucan, zymosan, showed similar activity. Addition of GRN directly to in vitro RAW 264.7 or proteose peptone induced peritoneal macrophage (PP-PEC) culture could not enhance NO synthesis. However, NO synthesis of PP-PEC was enhanced in vitro by addition of GRN in the presence of interferon gamma (IFN gamma). Gene expression of IFN gamma mRNA in the liver and PEC were enhanced in GRN administered mice assessed by reverse transcriptase assisted PCR (RT-PCR) method. These facts strongly suggested that beta-glucan has capacity to enhance NO synthesis of PM in vivo through IFN gamma mediated mechanism.

Signal transduction pathway on beta-glucans-triggered hydrogen peroxide production by murine peritoneal macrophages in vitro

It has been reported that the biological activities of several beta-glucans vary due to differences in their physicochemical properties. In this study we investigated the ability of beta-glucans to trigger H2O2 production and activate signaling pathway on peritoneal macrophages. The most effective beta-glucan tested on H2O2 production was zymocel which was a particulate preparation from the yeast cell wall. In contrast, gel-forming beta-glucans which are known as immunoenhancers did not trigger the H2O2 production by macrophages at all. To identify the related signaling pathway for the particulate beta-glucans-triggered H2O2 production, several inhibitors were applied. Hydrogen peroxide production triggered with phorbol myristate acetate was inhibited by pretreatment of macrophages with H-7, a protein kinase C inhibitor. However, beta-glucans-triggered H2O2 production was not affected by H-7. The results suggested that genistein-sensitive tyrosine kinase and bromophenacyl bromide-sensitive phospholipase A2 participated in the particulate beta-glucans-triggered H2O2 production, although the phagocytosis of particulate beta-glucans was not inhibited by either reagents. In conclusion, gel-forming (1-->3)-beta-D-glucans-induced activation was not sufficient to trigger H2O2 on macrophages, and pathways for particulate beta-glucans-triggered H2O2 production were regulated differently from those for phagocytosis of beta-glucans.

Blood clearance of (1-->3)-beta-D-glucan in MRL lpr/lpr mice

(1-->3)-beta-D-Glucans have a variety of biological and immunopharmacological properties, and they are used clinically as biological response modifiers (BRMs). Clinically, these glucans have often been used for long periods by multiple dosing. During studies on the clearance and metabolism of the glucans in mice, we have found that, in the case of a single dose, the glucan was cleared from blood eventually, and remained constant in the organs for at least one month. Here, we investigated the clearance of glucans from the blood following multiple dosing using MRL lpr/lpr mice with an autoimmune disease. Two kinds of glucans, GRN from Grifola frondosa and SSG from Sclerotinia sclerotiorum, were administered to the mice once a week for more than 35 weeks (250 micrograms/week/mouse by the intraperitoneal route). Examination of the blood clearance of the glucans in these mice revealed that the glucan concentrations were always high (about 20 micrograms/ml for GRN and 200 micrograms/ml for SSG). It is also shown that the glucans were significantly deposited in the liver and spleen of these mice. These findings suggest that administration of a large quantity of the glucan saturated the reticuloendothelial system, resulting in circulation of the glucan in the blood.

Inactivation of (1-->3)-beta-D-glucan in mice

Intraperitoneally or intravenously administered (1-->3)-beta-D-glucan remained in the liver and spleen, for a long time without major structural changes, but the priming activity to lipopolysaccharide (LPS)-triggered tumor necrosis factor-alpha (TNF-alpha) production was reduced more quickly. The relationship between the deposited glucan contents and the antitumor activity was examined by comparing kinetics of the activity using solid form Sarcoma 180 tumor in ICR mice. We used three kinds of soluble glucans, sonifilan (SPG), grifolan (GRN), and SSG, and a particulate glucan, zymosan (ZYM). These were administered 5 weeks before (-5W) the tumor inoculation and the tumor weight was compared 5 weeks after the inoculation. Compared with the activity of those administered at the optimum timing, all of the glucans reduced the activity about 5 fold, although significant activity still remained, especially in the case of SPG. Five weeks after intraperitoneal (SPG, GRN, SSG) or intravenous (ZYM) administration of the glucans, all were found in the liver and spleen in significant quantities. These facts strongly suggested that the activity of the glucan was reduced not only because of chemical/physical degradation but also a certain physiological inactivation mechanism.

Structure-activity relationship of (1-->3)-beta-D-glucans in the induction of cytokine production from macrophages, in vitro

In a previous study, we reported that one of the gel-forming (1-->3)-beta-D-glucans, grifolan (from Grifola frondosa, GRN), stimulated cytokine production from macrophages in vitro. However, several other gel-forming (1-->3)-beta-D-glucans, such as sonifilan (SPG) and SSG, did not induce cytokine production from macrophages. The ultrastructure of gel-forming (1-->3)-beta-D-glucans, especially the triple- and single-helix, does not affect the cytokine-inducing activity. The action on tumor necrosis factor alpha (TNF alpha) release was correlated with the molecular weight of GRN, since the highest molecular weight fraction of GRN, Mr > or = 45000, exhibited the strongest activity. Although, native SSG (Mr > or = 2000000) did not induce cytokine production, chemical modification involving debranching of the side chain glucosyl residues of SSG resulted in TNF alpha inducing activity. These results suggest that the branching ratio and molecular weight of (1-->3)-beta-D-glucans are important factors for the production of cytokines from macrophages. GRN-inducible TNF alpha release was reduced by co-culturing with SPG, SSG, or the soluble beta-glucan, laminarin (LAM). Pretreatment alone with SPG or LAM was not sufficient for significant inhibition of GRN-inducible TNF alpha release. TNF alpha production induced with 50 micrograms/ml of zymosan (ZyM) was also reduced by addition of SPG, but TNF alpha production, stimulated with a higher concentration (100 micrograms/ml) of ZyM or with lipopolysaccharide (LPS), was not reduced significantly. The inhibitory effect of LAM on the uptake of GRN by RAW264.7 cells was not completely correlated with TNF alpha release. These results suggest that macrophages may incorporate beta-glucans through certain (1-->3)-beta-D-glucan-specific mechanisms and/or other endocytosis pathways, and that the beta-glucan-specific route is partially associated with cytokine production. In conclusion, TNF alpha release by macrophages is induced only by beta-glucans with high molecular weights and lower branching ratios, and the mechanism for the recognition of beta-glucans is multiple and assumed to be divided into several parts involving various cellular functions.

Comparison of the immunopharmacological activities of triple and single-helical schizophyllan in mice

(1-->3)-beta-D-Glucans exhibit a variety of biological and immunopharmacological activities, and the significance of these activities is dependent on the structure of the glucans such as molecular weight, degree of branching, and conformation. Based on the generally accepted evidence that the conformation of clinically used Sonifilan (SPG) is a triple helix, we prepared alkaline treated SPG (SPG-OH) as a single helix conformer. In this report, we examined (A) the antitumor effect on a solid form tumor in vivo, (B) hematopoietic response on cyclophosphamide induced leukopenia, (C) antagonistic effect for zymosan mediated-hydrogen peroxide synthesis on peritoneal macrophage (PM), (D) priming effect of lipopolysaccharide (LPS) triggered tumor necrosis factor (TNF) synthesis, (E) nitric oxide synthesis of PM in vivo, and (F) hydrogen peroxide synthesis of PM in vivo. Both SPG and SPG-OH showed a significant effect on (A) and (B). The activity on (C) was stronger in SPG than SPG-OH. The activities of (D), (E), and (F) were stronger in SPG-OH. These facts strongly suggested that the glucan-mediated immunopharmacological activities were dependent on the helical conformation, and the conformation dependency varied dependent on the assays used.

Effect of soluble fungal (1-->3)-beta-D-glucan obtained from Sclerotinia sclerotiorum on alveolar macrophage activation

In this study, we examined the effect of systemic administration of SSG, a soluble highly branched (1-->3)-beta-D-glucan obtained from a fungus Sclerotinia sclerotiorum IFO 9395, on pulmonary immune responses in mice. SSG (10 mg/kg) administered intravenously (i.v.) rapidly leaked into the alveolar space and enhanced several functions of alveolar macrophages (AMs), such as phagocytic activity, lysosomal enzyme activity, active oxygen secretion and cytokine production, on day 1 post-administration. However, kinetic changes of influx of SSG into alveoli and AM activation after SSG treatment were different. The enhanced AM functions decreased to control value on day 2 when SSG still existed at the alveolar space. Additionally, a high dose (500 micrograms/ml) of SSG was needed to activate AMs in vitro. These data imply that the stimulation by SSG alone is not effective on AM activation. SSG administered i.v. also augmented interferon gamma (IFN gamma) mRNA expression in the lung tissue, and the kinetic change of the expression was similar to that of AM activation. Additionally, a synergistic effect of SSG and IFN gamma was observed on AM activation in vitro. It may be possible that IFN gamma produced by pulmonary T cells is one of the important factors for AM activation in vivo by SSG injection. Furthermore, SSG administered i.v. enhanced candidacidal activity and cytolytic activity against pulmonary metastatic Lewis lung carcinoma (3LL) cells of AMs, and inhibited significantly the experimental pulmonary metastasis of 3LL cells. These observations are very useful for the clinical application of SSG as a biological response modifier (BRM).

Resistance of highly branched (1-->3)-beta-D-glucans to formolysis

Small molecular weight (MW) glucan derivatives could be a useful tool for studying the mechanisms of beta-glucan mediated biological activity, especially as antagonists for a beta-glucan receptor. This paper described the stability of various (1-->6) branched (1-->3)-beta-D-glucans to formolysis in the preparation of small MW derivatives. The glucans used were curdlan (linear), pachyman (few branches), GRN (one branch in every third main chain unit; 2/6), SPG (2/6), SSG (3/6), and OL-2 (4/6). Curdlan and pachyman were easily degraded to oligosaccharides by degradation for 20 min at 100 degrees C by 90% formic acid. However, branched glucans, especially the highly branched glucans, SSG and OL-2, were significantly resistant to degradation, and the majority remained high MW. SSG required a longer period and/or a higher temperature (121 degrees C treatment) to produce small MW derivatives. Branched glucans were also resistant to zymolyase (an endo-(1-->3)-beta-D-glucan hydrolase) digestion. These facts suggest that the (1-->6)-beta-D-branched residues contribute to the glucans' resistance to formic acid degradation and zymolyase digestion.

Characterization of mitogenic substances in the hot water extracts of bupleuri radix

Bupleuri Radix is a commonly used medicinal plant in Kampo medicine, and its hot water extracts show mitogenic activity to murine lymphocytes. In this paper the mitogenic substances in the hot water extracts of Bupleuri Radix (Bup-HWE) were fractionated and characterized physicochemically and immunologically. Most of these substances were recovered from mol. wt of more than 200 kDA fraction (fr. C-13). Separation of fr. C-13 by phenol-water fractionation method gave water soluble and phenol soluble mitogenic substances. These substances showed the activity even in C3H/HeJ mice, and polymyxin B or lysozyme treatment did not abrogate the activity, suggesting that the active substances are not related to bacterial lipopolysaccharide. Treatment of the mitogenic substances recovered from the phenol layer with NaCLO2, a polyphenol degrading chemical, significantly reduced the activity, but pronase and pectinase treatments were not effective. The mitogenic substances in the water layer were active even after NaCLO2 treatment. These findings suggested that the mitogenic substances of Bup-HWE are large molecular weight polyphenolic compounds and polysaccharide. The mitogenic substances are suggested to be B cell mitogens.

Modulation of the antitumor effect and tissue distribution of highly branched (1-->3)-beta-D-glucan, SSG, by carrageenan

The action of carrageenan (CAR), a representative blocking reagent for phagocytes, on the antitumor effect and tissue distribution of highly branched (1-->3-beta-D-glucan, SSG, was examined. CAR inhibited the antitumor effect of intraperitoneally administered SSG only when applied before inoculation of the tumor, and had little effect when applied after tumor inoculation. A similar result was observed when SSG was administered intralesionally. In contrast, CAR had considerable effect on tissue distribution of i.p. SSG. The differences with respect to the results in normal mice were: 1) the distribution of SSG from the peritoneal cavity to the rest of the body was inhibited, 2) large numbers of peritoneal exudate cells (PEC) were produced and a relatively high concentration of 3H-SSG was found in the PEC fraction 48h after administration of 3H-SSG, 3) one week after administration, 3H-SSG was distributed to throughout the body but the amount of 3H-SSG distributed was lower than in normal mice, 4) a significant amount of 3H-SSG was recovered from ligaments (containing omental milky spots, peritoneum, mesentery and associated fat) in which negligible amounts were found in normal mice. The results suggest that the inhibition of the antitumor effect of SSG by CAR probably results from the prevention of the natural resistance of mice which is related to phagocytic function, and that the distribution of SSG to throughout the body is significantly modulated by CAR.

Structural analysis of alkaline-soluble polysaccharide, P-1, from the kernels of Prunus mume Sieb. et Zucc

A polysaccharide fraction extracted with cold 0.5 M NaOH from the kernels of Prunus mume exhibited some biological activities. A polysaccharide, P-1, was purified from the 0.5M NaOH extract by ion-exchange chromatography and gel-filtration. The results of the structural analysis of P-1 to determine the relationship between the activities and the structure are described in this paper. In the mild acid hydrolysis of P-1, the nondialyzable hydrolysate (I-3) believed to be its core portion was obtained. The yield of I-3 was 26.0% and contained 59.8% uronic acid as galacturonic acid (GalA). The neutral sugars of I-3 were composed of rhamnose, xylose and galactose in a molar ratio of 1.0:3.4:0.3 following analysis by gas-liquid chromatography. The molecular weight of I-3 was estimated to be ca. 14000 by gel-filtration on Toyopearl HW55F. I-3 exhibited the mitogenic activity toward spleen cells as well as P-1. These facts appeared to confirm that I-3 was the core part of P-1 and important for its biological activity. I-3 was successfully reduced by the Taylor and Conrad method to avoid so much repetition. Methylation analysis of the reduced hydrolysate by gas-liquid chromatography and gas chromatography-mass spectroscopy showed that the ratio of 1,4-linked galactopyranosyl and 1,3,4-linked galactopyranosyl residues were significantly increased in comparison with native I-3. These results suggested that I-3 was composed of 1,4- and 1,3,4-linked galacturonic acid residues in the main chain.

Metabolic 13C-labeling of an antitumor (1-->3)-beta-D-glucan, SSG, from Sclerotinia sclerotiorum IFO 9395

A (1-->3)-beta-D-glucan, SSG, from Sclerotinia sclerotiorum IFO 9395 was metabolically labeled using [1-13C] and [2-13C]glucose, and the fate of the 13C-label was examined by 13C-NMR spectroscopy. 13C-NMR spectra of metabolically labeled SSG (13C-SSG) showed that most of the 13C-label in glucose residues of 13C-SSG were recovered from the originally labeled sites of carbon in glucose residue, and suggested little rearrangement during take-up from the medium. In the case of poor SSG producing culture conditions (reduced shaking rate), 13C-glucose incorporation in SSG molecule was similar to that in the case of high SSG-producing culture conditions. In addition, significant amounts of 13C-labeled trehalose were found in 13C-NMR spectra of the mycelium cultured in both poor and high SSG-producing conditions. These results suggested that different culture conditions affected SSG production, but not the metabolism of glucose and the biosynthetic pathway of SSG.

Comparison of the blood clearance of triple- and single-helical schizophyllan in mice

(1-->3)-beta-D-Glucans exhibit a variety of biological and immunopharmacological activities, and the degree of these activities depends on the nature of the individual glucans e.q. molecular weight, degree of branching and conformation. Based on the generally accepted evidence that the conformation of Sonifilan (SPG) used clinically is a triple helix, we prepared alkali-denatured SPG (SPG-OH) as a single helix conformer. In this report, we measured the concentration of beta-glucan administered to mice by using a beta-glucan-specific reagent prepared from limulus amebocyte lysate (Gluspecy [G test], Seikagaku Corporation, Tokyo) and discuss the blood clearance of SPG and SPG-OH following intraperitoneal (i.p.) or intravenous (i.v.) administration. Comparing the clearance of SPG-OH from the blood with that of SPG, SPG-OH was removed faster than SPG following both i.p. and i.v. administration. This strongly suggests that the clearance of beta-glucans is dependent on their conformation.

Enhancement of LPS triggered TNF-alpha (tumor necrosis factor-alpha) production by (1-->3)-beta-D-glucans in mice

Effects of (1-->3)-beta-D-glucans on tumor necrosis factor-alpha (TNF-alpha) production in mice in vivo were investigated with or without triggering stimulation of lipopolysaccharide (LPS). Administration of grifolan (GRN) (100-250 micrograms/mouse) obtained from Grifola frondosa, did not elevate the TNF-alpha concentration in serum, but significantly elevated LPS (10 micrograms/mouse)-elicited TNF-alpha production in serum. The priming effect was observed as early as 2 h after administration and remained high for 3 weeks. The priming effect was dependent on the strain of mice, i.e. ICR, BALB/c, and MRL/lpr (15 weeks old) showed high response. In addition, GRN administration increased membrane-bound TNF-alpha assessed by Western blotting and flow cytometry. Comparing the activity using structurally related glucans obtained from other microorganisms, highly branched glucans, SSG isolated from Sclerotinia sclerotiorum IFO 9395 and OL-2 from Omphalia lapidescence significantly increased TNF-alpha production. Small molecular weight GRN derivatives prepared by heat degradation method showed weaker priming effect. These facts suggested that the glucans showed priming effect of TNF-alpha production in vivo and that this effect was related to the degree of branching and molecular weight.

Enhancement of cytokine production by macrophages stimulated with (1-->3)-beta-D-glucan, grifolan (GRN), isolated from Grifola frondosa

The ability of grifolan (GRN), a purified fungal (1-->3)-beta-D-glucan, to induce various cytokines from macrophages was examined in vitro. Interleukin-6 (IL-6) activity in supernatants from the culture of macrophage cell line, RAW264.7 was dependent on increasing doses of GRN. The level of IL-6 induced with 500 micrograms/ml of GRN was comparable to that induced with lipopolysaccharide (LPS) 10 micrograms/ml. Enhancement of the mRNA level of IL-6 by treatment with GRN was detected by reverse transcriptase-polymerase chain reaction (RT-PCR). The effect of GRN on production of IL-6 was also observed using peritoneal macrophages from C3H/HeJ mice which did not respond to endotoxins. This data suggested that the ability of GRN to activate IL-6 production of macrophages is not due to contamination of endotoxins in the preparation. Enhanced production of cytokine by GRN was observed not only with IL-6, but also with interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha). In the production of TNF alpha, GRN was more effective than LPS used in this study. Other soluble or gel-forming(1-->3)-beta-D-glucans from various sources did not enhance the production of such cytokines although they are structurally similar to GRN. The above results indicate that GRN is a novel macrophage activator which augments cytokine production without dependence on endotoxins.

Lysozyme regulates LPS-induced interleukin-6 release in mice

Bacterial lipopolysaccharide (LPS) stimulates the production and release of endogenous mediators [e.g., tumor necrosis factor (TNF), interleukins-1 and -6 (IL-1 and IL-6), and Platelet Activating Factor [PAF] responsible for the pathophysiologic changes and the mortality associated with sepsis. We recently demonstrated that lysozyme (LZM) bound to LPS (LZM-LPS complex) suppresses LPS-induced tumor necrosis factor-alpha (TNF-alpha) production in vivo. In the present study, we investigated the effect of LZM-LPS complex formation on LPS-induced IL-6 production, both in vitro and in vivo. With the addition of LZM-LPS complex, TNF-alpha and IL-6 release was significantly reduced compared with that by LPS in a dose-dependent manner in mouse macrophage-like cells, RAW264.7. IL-6 production in serum by LPS in carrageenan (CAR)-primed mice peaked at 2 hr following injection. LZM-LPS and LZM-Escherichia coli cell complex (as 1 microgram of LPS per mouse) released significantly reduced concentrations of IL-6 in serum (P < 0.01 and P < 0.001 versus CAR-pretreated LPS- or cell-injected mice). These results emphasize the important role of LZM in vivo in the neutralization of endotoxin. However, in the case of IL-6, by administration of a lethal dose of LPS (as 100 micrograms of LPS per mouse), the IL-6 level was reduced by LZM, but a significant concentration of IL-6 was still released; although the TNF- alpha concentration was negligible in this experimental condition. Thus, it is suggested that LZM might regulate the systemic inflammation induced during Gram-negative bacterial infections by inhibiting the release of cytokines in serum.

Preparation and antigen specificity of an anti-(1-->3)-beta-D-glucan antibody

Antibody for (1-->6)-branched (1-->3)-beta-D-glucan was prepared using rodents. An antitumor (1-->6)-beta-monoglucosyl branched (1-->3)-beta-D-glucan (GRN: grifolan) was conjugated with bovine serum albumin and used as an immunogen. The antibody titer in serum was determined by ELISA using biotin-conjugated GRN. Administration of the antigen raised the antibody titer only in the rabbit, with mouse and rat showing no significant antibody titer for the glucan. The antigen specificity of the anti-GRN antibody was determined by competitive ELISA. The rabbit anti-GRN antibody bound to structurally related antitumor (1-->6)-branched (1-->3)-beta-D-glucans such as lentinan, schizophyllan and SSG, whereas it did not react with linear (1-->3)-beta-D-glucan, curdlan or GRN-derivatives obtained by periodate-oxidation and Smith degradation. These facts strongly suggest that the hapten site of the antibody was the monoglucosyl branched moiety of (1-->3)-beta-D-glucan. These results indicate that this antibody would be a useful probe for the detection of (1-->6)-branched antitumor glucans administered to the host.

Detoxification of lipopolysaccharide (LPS) by egg white lysozyme

Recent studies carried out by our group suggest that lysozyme binds to bacterial lipopolysaccharide with a high affinity to produce a complex, and inhibits various biological activities of lipopolysaccharide. Although the basic structure of lipopolysaccharide is independent of the species and strains of Gram-negative bacteria, many structural factors such as O-antigenic polysaccharide, lipid A, substituted groups, and associated molecules, affect the biological activities of lipopolysaccharide. In this study, we prepared lysozyme/lipopolysaccharide complexes using various structures of lipopolysaccharide and compared the activity and physicochemical properties. Native and dansylated lysozyme were found to bind to all tested lipopolysaccharides. The mitogenic activity and TNF production by all tested lipopolysaccharides were significantly reduced by complex formation in vitro. Administration of the complex prepared by various lipopolysaccharides produced significantly less quantities of TNF in the septic shock model. These results suggested that binding of lysozyme to lipopolysaccharide is important for the host both in pathophysiological responses to lipopolysaccharides and in the modification of lipopolysaccharide biological activity.

Analysis of cytokine mRNAs induced by the administration of a highly branched (1-->3)-beta-D-glucan, OL-2

OL-2, a highly branched (1-->3)-beta-D-glucan, is an antitumor glucan showing strong hematopoietic activity with weaker adjuvant activity than schizophyllan (SPG), another antitumor glucan and one which is used clinically. This paper deals with the gene expression of cytokines in mice by OL-2 and SPG in order to characterize their immunopharmacological activity. Gene expression was examined by a reverse transcriptase-polymerase chain reaction method after intraperitoneal administration of OL-2 or SPG (250 micrograms/mouse). The OL-2 administered mice strongly expressed the interleukin 1 receptor antagonist (IL-1ra) gene but SPG administered mice did not. The difference would be strongly related to the antigen-specific response between OL-2 and SPG. In the genes related to haematopoiesis, OL-2 induced G-CSF and GM-CSF, but SPG induced IL-3. These differences would relate to the pattern of haematopoietic response. Comparing the cytokine gene expression in ICR and AKR mice by OL-2 administration, the changes in cytokine gene expression were less in AKR mice administered OL-2. These findings suggest that the immunopharmacological characteristics of OL-2 are closely related, at least in part, to the activation of the complement system. The data shown in this paper also suggest that cytokine gene expression by beta-glucan would be significantly affected by the structure of these glucans.

Changes in immune mediators in mouse lung produced by administration of soluble (1-->3)-beta-D-glucan

In this study, we showed that systemic administration of SSG, a highly branched soluble (1-->3)-beta-D-glucan obtained from Sclerotinia sclerotiorum, induced immunological changes in the alveolar space of mice in vivo, assessed by analysing some immune mediators in bronchoalveolar lavage (BAL) fluid. A single i.v. administration of SSG (250 micrograms/mouse) induced a rapid but transient leakage of the serum components, IgG and fibronectin, into the alveolar space. This was apparent 12 h post-administration and reached a peak on day 2. Similar kinetic changes were found for lysosomal enzyme activities and interferon gamma (IFN gamma) concentrations in BAL which are markers of activated alveolar macrophages (AMs) or pulmonary T cells. BAL prepared from SSG-treated mice stimulated lysosomal enzyme release from AMs in vitro. However, SSG did not provoke the chronic accumulation of serum proteins in alveoli and did not induce the release of detectable amounts of nitric oxide and the inflammatory cytokines, IL-1, IL-6 and TNF alpha, into BAL. However, their mRNAs were detected in lung tissue using the reverse-transcriptase polymerase chain reaction (RT-PCR) technique. Similar results were observed for multiple i.v. administration (250 micrograms, once a day for 10 consecutive days), and there were a little differences between single and multiple administration. In summary, systemic administration of SSG induces immune responses, including activation of AMs and lymphocytes, but does not provoke chronic inflammation in the alveolar space when administered either as single or multiple doses. This finding is very important for the clinical application of SSG in immunocompromised hosts as a biological response modifier (BRM) without toxic-side effects on lung tissue.

Induction of oral tolerance after feeding of ragweed pollen extract in mice

The induction of oral tolerance following the feeding of ragweed pollen and its extract was investigated in BALB/c mice. Antibody class-specific immune suppression could be observed, and the IgE response was specifically suppressed, depending on the amount of ragweed pollen extract fed when subsequently immunized with ragweed extract together with A1(OH)3 as an adjuvant. A multiple feeding was more effective than a single feeding of antigen, and the IgE response was completely suppressed when 20 mg of pollen extract was fed for 5 consecutive days. On the other hand, IgG production was not suppressed even though a large amount of ragweed pollen or its extract was fed. Furthermore, no secretion of antigen-specific IgA into saliva was observed in control animals or those fed ragweed pollen extract. Thus, pollen extract feeding may be potentially useful for the prophylaxis or therapy of allergic rhinitis induced by ragweed.

Binding of lysozyme to lipopolysaccharide suppresses tumor necrosis factor production in vivo

Endotoxin (lipopolysaccharide [LPS]) released during gram-negative bacterial infection induces varieties of cytokines which directly and/or indirectly cause shock, disseminated intravascular coagulation, and death. We previously showed that lysozyme (LZM) was an LPS-binding protein and inhibited various immunomodulating activities of LPS. In this study, we examined the effect of LZM on the LPS-triggered septic shock model induced by carrageenan treatment and assessed by tumor necrosis factor production. The data presented in this report strongly suggest that LZM-LPS complex formation completely abrogates tumor necrosis factor production and the mortality caused by LPS and that LZM may be useful for the treatment of endotoxin shock.

Biological activity and structural characterization of alkaline-soluble polysaccharides from the kernels of Prunus mume Sieb. et Zacc

The fruits of Prunus mume Sieb. et Zacc. (Japanese name, ume) have been used as a traditional drug and health food. In order to study the active components of P. mume, the polysaccharide fractions were extracted with cold water, hot water and aqueous sodium hydroxide from the kernels of P. mume. We found that some of the polysaccharide fractions exhibited various types of biological activities such as mitogenesis, activation of the alternative pathway of complement and activation of clot formation in human plasma. A polysaccharide, P-1, obtained from the cold 0.5 M NaOH extract was purified by ion-exchange chromatography and gel-filtration, P-1 contained 62.0% neutral sugar as glucose and 38.4% uronic acid (as galacturonic acid), and was free from protein. The neutral sugars of P-1 were arabinose, xylose, rhamnose and galactose in a molar ratio of 9.4:3.4:1.1:1.0, following analysis by gas-liquid chromatography. In addition, galacturonic acid was identified by thin-layer chromatography. The molecular weight of P-1 was found to be more than 2,000,000 by gel-filtration on Toyopearl HW 65F. P-1 showed mitogenic activity towards spleen cells of both C3H/HeN and C3H/HeJ, suggesting that it was free from bacterial endotoxic lipopolysaccharides.

Preparation and properties of metabolically 3H- or 13C-labeled (1-->3)-beta-D-glucan, SSG, from Sclerotinia sclerotiorum IFO 9395

Metabolically labeled (1-->3)-beta-D-glucan (SSG) obtained from the culture filtrate of Sclerotinia sclerotiorum IFO 9395, with the radio (3H) or the stable isotope (13C) was prepared. The specific radioactivity of 3H-SSG was increased in accordance with the amount of D-[3H]glucose added, and was 15-20 kBq/mg SSG when 222 kBq/mL of D-[3H]glucose was added. Physicochemical analyses of 3H-SSG suggested a structural similarity between SSG and 3H-SSG. 13C NMR spectra of 13C-labeled SSG (13C-SSG) revealed that a strong signal of the 13C-nucleus was observed at the C-1 or C-2 position when D-[1-13C]glucose or D-[2-13C]glucose was used, respectively, suggesting that most of the glucose residues in SSG were directly taken up from the medium. In addition, part of the 13C-nucleus was incorporated into the SSG molecule at all carbon atoms after metabolic degradation and reconstruction of the glucose molecule. Analyses of the culture filtrate and the mycelium of the fungus suggested that part of the glucose was also metabolized to trehalose and mannitol.