The pectic polysaccharide from Bupleurum falcatum L. enhances immune-complexes binding to peritoneal macrophages through Fc receptor expression

Extraction, purification, structure characteristics, biological activities and pharmaceutical application of Bupleuri Radix Polysaccharide: A review

Bupleuri Radix (BR), as a well-known plant medicine of relieving exterior syndrome, has a long history of usage in China. Bupleuri Radix Polysaccharide (BRP), as the main component and an important bioactive substance of BR, has a variety of pharmacological activities, including immunoregulation, antioxidant, antitumor, anti-diabetic and anti-aging, etc. In this review, the advancements on extraction, purification, structure characteristics, biological activities and pharmaceutical application of BRP from different sources (Bupleurum chinense DC., Bupleurum scorzonerifolium Willd., Bupleurum falcatum L. and Bupleurum smithii Woiff. var. Parvifolium Shan et Y. Li.) are summarized. Meanwhile, this review makes an in-depth discussion on the shortcomings of the research on BRP, and new valuable insights for the future researches of BRP are proposed.

Polypotency of the immunomodulatory effect of pectins

Pectins are the major component of plant cell walls, and they display diverse biological activities including immunomodulation. The pectin macromolecule contains fragments of linear and branched regions of polysaccharides such as homogalacturonan, rhamnogalacturonan-I, xylogalacturonan, and apiogalacturonan. These structural features determine the effect of pectins on the immune system. The backbones of pectic macromolecules have immunosuppressive activity. Pectins containing greater than 80% galacturonic acid residues were found to decrease macrophage activity and inhibit the delayed-type hypersensitivity reaction. Branched galacturonan fragments result in a biphasic immunomodulatory action. The branched region of pectins mediates both increased phagocytosis and antibody production. The fine structure of the galactan, arabinan, and apiogalacturonan side chains determines the stimulating interaction between pectin and immune cells. This review summarizes data regarding the relationship between the structure and immunomodulatory activity of pectins isolated from the plants of the European north of Russia and elucidates the concept of polypotency of pectins in native plant cell walls to both stimulate and suppress the immune response. The possible mechanisms of the immunostimulatory and anti-inflammatory effects of pectins are also discussed.

Traditional Use, Pharmacology, Toxicology, and Quality Control of Species in Genus Bupleurum L

Many species of genus Bupleurum L. have been pharmaceutically used mainly in Asia and Europe for thousand years. Their roots are the most popular ingredients in Chinese materia medica prescriptions for the treatment of inflammatory diseases and auto-immune diseases. A plenty of chemical constituents have been isolated and identified from the species in Bupleurum L., such as saikosaponins, polysaccharides, volatile oils, flavonoids, polyacetylenes, lignins, and coumarins, most of which possess a variety of biological activities, especially for the hepatoprotective effect, antitumor activity, immunoregulation, and febrifuge efficacy. Therefore, the species in genus Bupleurum L. could be potential herbs of immunomodulator, antineoplastic, anti-oxidant, etc. Meanwhile, as potential toxicities have been discovered in some constituents, it is urgent to establish a comprehensive quality evaluation system to ensure the safety and efficiency of herbs. This paper reviews on the phytochemical and pharmacological studies, especially for the toxicology and quality control of the species in Bupleurum L., which is a reference for the species in this genus for safe usage and further development.

Bupleurum chinense DC polysaccharides attenuates lipopolysaccharide-induced acute lung injury in mice

Bupleurum chinense DC had hepato-protective, anti-inflammatory, antipyretic, analgesic, and immunomodulatory effect in traditional Chinese medicine. This study was to determine whether the crude polysaccharides isolated from the roots of Bupleurum chinense DC (BCPs) attenuated lipopolysaccharide (LPS)-induced acute lung injury in mice. Mice were challenged with LPS intratracheally 2h before BCPs (20, 40 and 80 mg/kg) administration. The bronchoalveolar lavage fluid (BALF) was collected 24h after LPS challenge. Treatment with BCPs reduced lung wet-to-dry weight ratio. The elevated number of total cells and protein concentration in BALF was reduced. The increased level of myeloperoxidase (MPO), tumor necrosis factor-α (TNF-α) in BALF, and serum nitric oxide (NO) were also inhibited. BCPs significantly attenuated lung injury with improved lung morphology and reduced complement deposition. These results suggested that the effect of BCPs against ALI might be related with its inhibitory effect on excessive activation of complement and on the production of proinflammatory mediators.

Toll-like receptor 4-dependent adjuvant activity of Kakkon-to extract exists in the high molecular weight polysaccharide fraction

Kakkon-to, a traditional herbal medicine (Kampo formula), has been used historically in China and Japan for the treatment of infectious diseases such as influenza and the common cold. However, the biological mechanism of its therapeutic action has not yet been elucidated. In this study, we investigated the immunological function of Kakkon-to and found that the high molecular weight fraction of the extract activated macrophages in vitro. This fraction was found to be composed primarily of saccharides and in vitro intensively stimulated mouse peritoneal macrophages that produce Th1 inflammatory cytokines such as tumor necrosis factor α (TNFalpha), interleukin-1beta (IL-1beta), interferon-gamma (IFN-gamma), and interleukin-6 (IL-6). The fraction did not activate macrophages from C3H/HeJ lacking Toll-like receptor 4 (TLR4) or MyD88-deficient mice, indicating that macrophage activation by the fraction was mediated by TLR4. The route of administration of the fraction into mice regulated the kinetics of TNFalpha production in immune organs. Intravenous administration induced TNFalpha production in the four target organs of spleen, liver, lung, and Peyer’s patch; however, the most abundant production occurred in the liver and peaked at 30-60 min post administration. Peritoneal administration induced similar kinetics but the most abundant production occurred in the spleen. In contrast, oral administration induced TNFalpha production in the liver, lung, and Peyer’s patch, but not in the spleen. Although liver and lung are TNFalpha-abundant organs, production peaks in these organs occurred later than in Peyer’s patch. We also found that the fraction induced antibody production as an adjuvant against a specific antigen ovalbumin (OVA) when administered simultaneously and subcutaneously in a dose-dependent manner. Interestingly, the fraction induced IgG-class antibody in response to low doses of the antigen, which induced only IgM-class antibody when administered alone, suggesting that the fraction induces a class switch of immunoglobulin as an adjuvant in vivo. The high molecular weight fraction of Kakkon-to extract could be applicable as a potent immunostimulating drug and adjuvant.

Stimulatory effect of a pectic polysaccharide from a medicinal herb, the roots of Bupleurum falcatum L., on G-CSF secretion from intestinal epithelial cells

The inner surface of the intestinal tract possesses a large area of mucosal membranes, and the intestinal epithelial cells exist at the interface between an antigen-rich lumen and a lymphocyte-rich lamina propria. The crosstalk that occurs between these compartments serves to maintain intestinal homeostasis, and the cytokine network plays an important role in the crosstalk. In this study, the effect of a pectic polysaccharide, bupleuran 2IIc from Bupleurum falcatum L., on cytokine secretion of intestinal epithelial cells was investigated in vitro. When murine normal colonic epithelial cell line MCE301 cells were stimulated with bupleuran 2IIc, the contents of granulocyte colony-stimulating factor (G-CSF) in the conditioned medium were significantly increased in dose- and time-dependent manners. The enhanced G-CSF gene transcription in MCE301 cells by the stimulation of bupleuran 2IIc was observed by RT-PCR. The enhanced G-CSF secretion by bupleuran 2IIc was also observed in C3H/HeJ mice derived primary cultured colonic epithelial cells. Bupleuran 2IIc was digested with endo-(1-->4)-alpha-D-polygalacturonase, and the resulting bupleuran 2IIc/PG-1 ("ramified" region) showed potent G-CSF secretion enhancing activity. The activity of bupleuran 2IIc/PG-1 disappeared after the removal of arabinosyl residues from bupleuran 2IIc/PG-1 by endo-(1-->5)-alpha-L-arabinanase digestion. These results suggest that the "ramified" region (bupleuran 2IIc/PG-1) is the active site for the G-CSF secretion enhancing activity of bupleuran 2IIc, and the arabinan moiety of bupleuran 2IIc/PG-1 plays an important role in expression of the activity.

Inhibition of neutrophil adhesion by pectic galacturonans

The inhibition of the adhesion of neutrophils to fibronectin by the fragments of the main galacturonan chain of the following pectins was demonstrated: comaruman from the marsh cinquefoil Comarum polustre, bergenan from the Siberian tea Bergenia crassifolia, lemnan from the duckweed Lemna minor, zosteran from the seagrass Zostera marina, and citrus pectin. The parent pectins, except for comaruman, did not affect the cell adhesion. Galacturonans prepared from the starting pectins by acidic hydrolysis were shown to reduce the neutrophil adhesion stimulated by phorbol 12-myristate 13-acetate (1.625 microM) and dithiothreitol (0.5 mM) at a concentration of 50-200 microg/ml. The presence of carbohydrate chains with molecular masses higher than 300, from 100 to 300, and from 50 to 100 kDa in the galacturonan fractions was proved by membrane ultrafiltration.

Separation and isolation methods for analysis of the active principles of Sho-saiko-to (SST) oriental medicine

Sho-saiko-to (SST) was introduced into Japan as an oriental classical medicine from China approximately 1500 years ago, and it is currently the most representative Kampo medicine (traditional Japanese medicine). SST is manufactured in Japan as an ethical drug on a modern industrial scale in which the quality of ingredients is standardized with Good Manufacturing Practices (GMP) regulation. SST is widely used for the treatment of chronic hepatitis. Experimental and clinical studies including multi-center, placebo-controlled, double-blind studies have demonstrated the various pharmacological effects of SST. SST is prepared from the hot water extraction of seven raw materials, therefore many kinds of constituents are included. Three-dimensional (3D) HPLC analysis is useful for obtaining many kinds of constituents, especially low molecular ultraviolet (UV) quenching compounds, contained in SST as well as its fractions. Fingerprint pattern provided by 3D HPLC analysis makes possible to identify the overall-viewing of SST. Databases of UV spectra of the components of medicinal herbs obtained by reversed-phase (RP) HPLC using a photodiode array (PDA) and fingerprint patterns of crude drugs made by 3D HPLC analysis facilitate the identification, analysis and quality of herbal drugs. Studies using both PDA HPLC and an amino acid analysis with a fluorometric detector have found that SST contains fifteen major low molecular compounds (i.e. baicalin, wogonin-7-O-glucuronide, liquiritin, their three aglycons, liquiritin apioside, glycyrrhizin, saikosaponin b1, saikosaponin b2, ginsenoside Rg1, ginsenoside Rb1, (6)-gingerol, (6)-shogaol and arginine). These compounds have various pharmacological actions, and are assumed to be responsible, at least partly, for the pharmacological effects of SST. Although there have only been a few investigations on high molecular compounds with pharmacological actions contained in SST, several kinds of polysaccharides have been isolated from constituent herbs of SST. This review paper summarizes analytical methods of separation, isolation and identification of compounds with biological activities from SST, which is a mixture drug of medicinal herbs. Accordingly, this paper would not focus on methods of separation, isolation and analysis of particular compounds from each constituent herb of SST.

Methods for obtaining neutral and acid oligosaccharides from flax pectins

Esterified acid soluble pectins from flax (Linun usitatissimum L.) were degraded either with HCl or pectin lyase. Centrifugation and 2-propanol precipitation led to the isolation of two low molecular weight polygalacturonates after acid hydrolysis of pectins. However, after pectin lyase digestion and purification by size-exclusion HPLC, (1)H NMR analyses indicated that acetylated hairy regions, large methylated and acetylated oligogalacturonides together with small unsubstituted oligogalacturonides were produced. Thus, in a few steps, a panel of substituted neutral and acidic oligosaccharides was produced from a raw plant material. Such oligosaccharides could be useful for further fractionations such as chemical saponification and enzymatic removal of neutral sugar chains from the hairy regions. The procedures used for pectin extraction, for degradation, and for the purification of fragments seem appropriate for large-scale production of biologically active oligosaccharides from flax.

Separation and isolation methods for analysis of the active principles of Sho-saiko-to (SST) oriental medicine

Sho-saiko-to (SST) was introduced into Japan as an oriental classical medicine from China approximately 1500 years ago, and it is currently the most representative Kampo medicine (traditional Japanese medicine). SST is manufactured in Japan as an ethical drug on a modern industrial scale in which the quality of ingredients is standardized with Good Manufacturing Practices (GMP) regulation. SST is widely used for the treatment of chronic hepatitis. Experimental and clinical studies including multi-center, placebo-controlled, double-blind studies have demonstrated the various pharmacological effects of SST. SST is prepared from the hot water extraction of seven raw materials, therefore many kinds of constituents are included. Three-dimensional (3D) HPLC analysis is useful for obtaining many kinds of constituents, especially low molecular ultraviolet (UV) quenching compounds, contained in SST as well as its fractions. Fingerprint pattern provided by 3D HPLC analysis makes possible to identify the overall-viewing of SST. Databases of UV spectra of the components of medicinal herbs obtained by reversed-phase (RP) HPLC using a photodiode array (PDA) and fingerprint patterns of crude drugs made by 3D HPLC analysis facilitate the identification, analysis and quality of herbal drugs. Studies using both PDA HPLC and an amino acid analysis with a fluorometric detector have found that SST contains fifteen major low molecular compounds (i.e. baicalin, wogonin-7-O-glucuronide, liquiritin, their three aglycons, liquiritin apioside, glycyrrhizin, saikosaponin b1, saikosaponin b2, ginsenoside Rg1, ginsenoside Rb1, (6)-gingerol, (6)-shogaol and arginine). These compounds have various pharmacological actions, and are assumed to be responsible, at least partly, for the pharmacological effects of SST. Although there have only been a few investigations on high molecular compounds with pharmacological actions contained in SST, several kinds of polysaccharides have been isolated from constituent herbs of SST. This review paper summarizes analytical methods of separation, isolation and identification of compounds with biological activities from SST, which is a mixture drug of medicinal herbs. Accordingly, this paper would not focus on methods of separation, isolation and analysis of particular compounds from each constituent herb of SST.

Induction of cell cycle regulatory proteins by murine B cell proliferating pectic polysaccharide from the roots of Bupleurum falcatum L

Bupleuran 2IIc, a pectic polysaccharide isolated from the roots of Bupleurum falcatum L., was characterized as a T-cell-independent B cell mitogen, that activates, proliferates and differentiates B cells in vivo and in vitro (Immunology 97 (1999) 540). Studies were focused on elucidating the mechanism by which bupleuran 2IIc causes proliferation of B cells and expression of cell cycle regulatory proteins. B cells showed slower rates of entry into the S and G2/M phases of the cell cycle when stimulated with bupleuran 2IIc versus anti-IgM. However, the Stimulation Index continued up to two times longer with bupleuran 2IIc over anti-IgM. Although both bupleuran 2IIc and anti-IgM induced similar expressions of cell cycle regulatory proteins, cyclins D2, A, and B1, in B cells, those cells stimulated with bupleuran 2IIc appeared to sustain expressions of these protein for longer periods of time. Stimulation of B cells with bupleuran 2IIc induced phosphorylation of retinoblastoma protein, pRB, an important gene product regulating the restriction point, R, which is responsible for the transition from the G0/G1 to the S phases of the cell cycle. The results of this study demonstrate that both bupleuran 2IIc and anti-IgM interact with B cells, thus, leading to expressions of cell cycle regulatory proteins. However, the respective modes of binding and proximity of interactions with the B cell membrane may differ.

Effects of a pectic polysaccharide from a medicinal herb, the roots of Bupleurum falcatum L. on interleukin 6 production of murine B cells and B cell lines

The effect of T-cell-independent B cell mitogen, a pectic polysaccharide, bupleuran 2IIc, from a medicinal herb, the roots of Bupleurum falcatum L. on interleukin 6 (IL-6) production of murine B cells and B cell lines was investigated in order to clarify the mechanism of enhanced immunoglobulin (Ig) secretion from B cells. Bupleuran 2IIc enhanced IgM secretion from highly purified murine normal B cells. When normal B cells from murine spleen were cultured with bupleuran 2IIc in the presence of anti-IL-6 neutralizing antibody, the enhanced IgM secretion by bupleuran 2IIc was reduced. When B cells were stimulated with bupleuran 2IIc, their IL-6 secretion and the transcription of IL-6 mRNA were enhanced. The enhanced IL-6 secretion by bupleuran 2IIc was also observed in B cell line, Y16 cell. When bupleuran 2IIc was digested with endo-alpha-(1-->4)-D-polygalacturonase, the resulting enzyme resistant carbohydrate portion, "ramified" region (PG-1) composed of rhamnogalacturonan core containing neutral sugar side chains showed potent IL-6 secretion-enhancing activity. These results suggest that the "ramified" region of bupleuran 2IIc stimulates the secretion of IL-6 as the active site, and the resulting IL-6 may partially contribute the enhancement of IgM secretion as an autocrine and/or paracrine mechanism.

B-cell proliferation activity of pectic polysaccharide from a medicinal herb, the roots of Bupleurum falcatum L. and its structural requirement

Pectic polysaccharide fraction (BR-2) containing pharmacologically active pectic polysaccharide, bupleuran 2IIc, which was prepared from a medicinal herb, the roots of Bupleurum falcatum L., was administered orally to C3H/HeJ mice for 7 consecutive days. Proliferative responses of spleen cells were enhanced in the presence of the purified pectic polysaccharide, bupleuran 2IIc, but another B-cell mitogen, lipopolysaccharide (LPS) did not give a similar effect. In vitro studies using spleen cells showed that bupleuran 2IIc also stimulated lymphocytes, depleted of adherent cells or T cells. Bupleuran 2IIc treatment increased subpopulation of CD25+ and surface immunoglobulin M-positive (sIgM+) lymphocytes. Non-specific immunoglobulin secretion of spleen cells treated with bupleuran 2IIc was increased according to the culture time, and coexistence of interleukin-6 (IL-6) enhanced the secretion more than that of bupleuran 2IIc alone. These results suggest that bupleuran 2IIc proliferates B cells in the absence of macrophages, and the resulting activated B cells are then induced into antibody-forming cells in the presence of IL-6. Among the structural region of bupleuran 2IIc, ramified region (PG-1), which consists of rhamnogalacturonan core rich in neutral sugar chain, showed the potent mitogenic activity suggesting it to be an active site. Mitogenic activity of bupleuran 2IIc was reduced in the presence of antipolysaccharide antibody (antibupleuran 2IIc/PG-1-IgG), which recognizes the ramified region of bupleuran 2IIc as the antigenic epitope. Mitogenic activity of bupleuran 2IIc was also reduced by the addition of beta-d-GlcpA-(1-->6)-beta-d-Galp-(1-->6)-d-Galp or beta-d-GlcpA-(1-->6)-d-Galp, which are a part of the epitopes of antibupleuran 2IIc/PG-1-IgG. These results suggest that the epitopes in bupleuran 2IIc act as active sites of the polysaccharide during mitogenic activity.

Characterization of antigenic epitopes in anti-ulcer pectic polysaccharides from Bupleurum falcatum L. using several carbohydrases

A polyclonal antibody (anti-bupleuran 2IIc/PG-1-IgG) against the "ramified" region (PG-1) of an anti-ulcer pectic polysaccharide was prepared and its antigenic epitopes were analyzed by using several carbohydrases. Enzymatic removal of arabinosyl residues from PG-1 by endo-(1-->5)-alpha-L-arabinanase (from Aspergillus niger) did not reduce the binding ability of anti-bupleuran 2IIc/PG-1-IgG to PG-1. When the endo-(1-->5)-alpha-L-arabinanase-resistant fraction (EA-1) was digested with rhamnogalacturonase A (rRGase A from A. aculeatus), a high-molecular-mass fragment fraction (RA-1) and an oligosaccharide fraction (RA-3) were obtained. RA-3 contained at least four kinds of oligosaccharides liberated from the rhamnogalacturonan core. This partial removal of the rhamnogalacturonan core in EA-1 also did not reduce the binding of the antibody to the polysaccharide. Further digestion of RA-1 with exo-(1-->3)-beta-D-galactanase (from Irpex lacteus), gave a high-molecular-mass fragment (EXG-1) and a trace of oligosaccharides (EXG-3). Methylation and FABMS analyses indicated that EXG-3 contained mono- and di-galactosyl oligosaccharides possessing terminal GlcA or GlcA4Me. Removal of the EXG-3 fraction from RA-1 by exo-(1-->3)-beta-D-galactanase significantly reduced the ability of the binding of the antibody to the polysaccharide. When PG-1 was digested with endo-(1-->6)-beta-D-galactanase (from Trichoderma viride) or beta-D-glucuronidase (from A. niger), the reactivities of both enzyme-resistant fractions to the antibody were decreased in comparison with that of PG-1. Both radish arabinogalactan (containing GlcA4Me) and beta-D-GlcpA-(1-->6)-beta-D-Galp-(1-->6)-D-Galp were shown to inhibit the reactivity of PG-1 to the antibody by competitive ELISA. These results suggest that 6-linked galactosyl chains containing terminal GlcA or GlcA4Me attached to (1-->3)-beta-D-galactosyl chains, are important sugar residues in the antigenic epitopes of the "ramified" region of bupleuran 2IIc.

Rhamnogalacturonan II from the leaves of Panax ginseng C.A. Meyer as a macrophage Fc receptor expression-enhancing polysaccharide

A complex pectic polysaccharide (GL-4IIb2) has been isolated from the leaves of Panax ginseng C.A. Meyer, and shown to be a macrophage Fc receptor expression-enhancing polysaccharide. The primary structure of GL-4IIb2 was elucidated by composition. 1H NMR, methylation, and oligosaccharide analyses. GL-4IIb2 consisted of 15 different monosaccharides which included rarely observed sugars, such as 2-O-methylfucose, 2-O-methylxylose, apiose, 3-C-carboxy-5-deoxy-L-xylose (aceric acid, AceA), 3-deoxy-D-manno-2-octulosonic acid (Kdo), and 3-deoxy-D-lyxo-2-heptulosaric acid (Dha). Methylation analysis indicated that GL-4IIb2 comprised 34 different glycosyl linkages, such as 3,4-linked Fuc, 3- and 2,3,4-linked Rha, and 2-linked GlcA, which are characteristic of rhamnogalacturonan II (RG-II). Sequential degradation using partial acid hydrolysis indicated that GL-4IIb2 contained alpha-Rhap-(1-->5)-Kdo and Araf-(1-->5) Dha structural elements, an AceA-containing oligosaccharide, and uronic acid-rich oligosaccharide chains in addition to an alpha-(1 -->4)-galacturono-oligosaccharide chain. FABMS and methylation analyses suggested that the AceA-containing oligosaccharide was a nonasaccharide in which terminal Rha was additionally attached to position 3 of 2-linked Arap of the octasaccharide chain observed in sycamore RG-II. Component sugar and methylation analyses assumed that the uronic acid-rich oligosaccharides possessed a similar structural feature as those in sycamore RG-II. GL-4IIb2 had a larger molecular mass (11,000) than sycamore RG-II (approximately 5000).

Regulation of immune complexes binding of macrophages by pectic polysaccharide from Bupleurum falcatum L.: pharmacological evidence for the requirement of intracellular calcium/calmodulin on Fc receptor up-regulation by bupleuran 2IIb

The pectic polysaccharide, bupleuran 2IIb, up-regulates Fc-receptor (FcR) expression on peritoneal macrophages in a dose-dependent manner. The intracellular signal transduction by bupleuran 2IIb leading to the expression of FcR was studied. Neither the protein kinase C (PKC) inhibitor, 1-(5-isoquinolinylsulphonyl)-2-methylpiperazine dihydrochloride, nor the structurally distinct PKC antagonist, calphostin C, inhibited bupleuran 2IIb-induced up-regulation of FcR, whereas two direct activators of PKC, L-alpha-1-oleoyl-2-acetyl-sn-3-glycerol and N-(6-phenylhexyl)-5-chloro-1-naphthalenesulphonamide were unable to up-regulate the expression of FcR. The protein kinase A (PKA) inhibitor, N-[2-(methylamino)ethyl]-5-isoquinolinesulphonamide dihydrochloride also did not inhibit bupleuran 2IIb-induced up-regulation of FcR. Fluorescence image analysis using the calcium-sensitive dye, Fura-2, demonstrated that bupleuran 2IIb induced a rapid increase in intracellular levels of calcium (Ca2+). When macrophages were treated with calcium antagonist, 8-(diethylamino)-octyl-3,4,5-trimethoxybenzoate hydrochloride, bupleuran 2IIb-induced up-regulation of FcR was inhibited in a dose-dependent manner. The bupleuran 2IIb-induced up-regulation of FcR was also blocked by two structurally distinct calmodulin antagonists, trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide hydrochloride. Furthermore, elevation of intracellular Ca2+ using the calcium ionophore, A23187, led to up-regulation of the FcR expression in a dose-dependent manner. These results suggest that bupleuran 2IIb induces the up-regulation of FcR on macrophages by a mechanism dependent on an increase in intracellular Ca2+ followed by activation of the calmodulin, but not by a PKC or PKA pathway.