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Immune reactions in polysaccharide media. Polysaccharide-enhanced precipitin reactions with antigens of various sizes.

ABSTRACT: The influence of the size of the antigen in the polysaccharide-enhanced precipitin reaction was investigated. The experiments were carried out by addition of homologous antigens of different molecular sizes (the monomer, dimer and trimer of serum albumin and the monomer and dimer of immunoglobulin G) to the same preparation of antibody in the absence and presence of dextran. Dextran decreased the solubility of the immune complexes to a larger extent when the antigen size increased. This is in accord with the view that the polysaccharide effect is due to steric exclusion.

SUBMITTER: Hellsing K

PROVIDER: S-EPMC1184807 | biostudies-other | 1969 Aug

REPOSITORIES: biostudies-other

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Immune reactions in polysaccharide media. The composition of the antigen-antibody complexes in the precipitin reaction.

Project description:The precipitin reaction is enhanced in the presence of polysaccharides (Hellsing, 1966). This reaction has now been studied in detail with labelled antigen ((125)I-labelled human serum albumin) and antibody ((131)I-labelled rabbit anti-albumin immunoglobulin G). The relative proportions of antigen and antibody in the precipitates are unchanged by the addition of dextran in spite of the increased precipitation. The ratio of antibody to antigen in the soluble immune complexes decreases with increasing polysaccharide concentration. This can be interpreted as a decrease in the aggregate size of the complexes. At the same time the amount of free antigen in the solution increases. The results are consistent with a decrease in solubility, primarily of the large immune aggregates, together with a shift in the equilibrium between small and large complexes. The effect is in accord with a steric-exclusion phenomenon.

| S-EPMC1184806 | biostudies-other

Immune reactions in polysaccharide media. The effect of hyaluronate, chondroitin sulphate and chondroitin sulphate-protein complex on the precipitin reaction.

Project description:The influence of the connective-tissue polysaccharides hyaluronate, chondroitin 4-sulphate and a chondroitin 4-sulphate-protein complex (PP-L) from cartilage on the precipitin reaction was investigated. In a system consisting of (125)I-labelled human serum albumin and the immunoglobulin G fraction from rabbit anti-albumin sera, the precipitation is greatly increased in the region of antigen excess. This effect depends on the concentration, molecular weight and configuration of the polysaccharide. The increase parallels a decrease in the amount of soluble immune complexes in the supernatant. It is suggested that the effect is due to steric exclusion of the complexes from the domains of the polysaccharides. The possibility that such a mechanism might enhance precipitation of antigen-antibody complexes in certain pathological conditions is discussed.

| S-EPMC1187735 | biostudies-other

Immune reactions in polysaccharide media. Experiments with specific antibodies of different affinities for serum albumin.

Project description:Rabbit antibody fractions of different affinities for human serum albumin were prepared by an immunosorbent technique. The fractions were used in studies on the enhancement of the precipitin reaction by polymers. Dextran increased the immune precipitation to about the same extent regardless of whether antibodies with high and low affinities were used. The effect should considerably facilitate the detection of antibodies with low precipitating ability in immunological assays. The results are discussed in terms of a steric-exclusion mechanism.

| S-EPMC1184808 | biostudies-other

Immune reactions in polysaccharide media. Investigation on complex-formation between some polysaccharides, albumin and immunoglobulin G.

Project description:Serum albumin and immunoglobulin G were chromatographed on columns of dextran, hyaluronate and chondroitin 4-sulphate. The partition of the two proteins between hyaluronate and buffer was also measured by equilibrium dialysis. The results accord with the view that there is no complex-formation between the polysaccharides and the proteins in 0.05m-phosphate buffer, pH7.4, containing sodium chloride (0.1m). The observations support the hypothesis that the previously described polysaccharide enhancement of the precipitin reaction is due to exclusion and not to non-specific complex-formation.

| S-EPMC1187736 | biostudies-other

Enhanced Immunogenicity of Engineered HER2 Antigens Potentiates Antitumor Immune Responses.

Project description:For cancer vaccines, the selection of optimal tumor-associated antigens (TAAs) that can maximize the immunogenicity of the vaccine without causing unwanted adverse effects is challenging. In this study, we developed two engineered Human epidermal growth factor receptor 2 (HER2) antigens, K965 and K1117, and compared their immunogenicity to a previously reported truncated HER2 antigen, K684, within a B cell and monocyte-based vaccine (BVAC). We found that BVAC-K965 and BVAC-K1117 induced comparable antigen-specific antibody responses and antigen-specific T cell responses to BVAC-K684. Interestingly, BVAC-K1117 induced more potent antitumor activity than the other vaccines in murine CT26-HER2 tumor models. In addition, BVAC-K1117 showed enhanced antitumor effects against truncated p95HER2-expressing CT26 tumors compared to BVAC-K965 and BVAC-K684 based on the survival analysis by inducing T cell responses against intracellular domain (ICD) epitopes. The increased ICD epitope-specific T cell responses induced by BVAC-K1117 compared to BVAC-K965 and BVAC-K684 were recapitulated in human leukocyte antigen (HLA)-untyped human PBMCs and HLA-A*0201 PBMCs. Furthermore, we also observed synergistic antitumor effects between BVAC-K1117 and anti-PD-L1 antibody treatment against CT26-HER2 tumors. Collectively, our findings demonstrate that inclusion of a sufficient number of ICD epitopes of HER2 in cellular vaccines can improve the antitumor activity of the vaccine and provide a way to optimize the efficacy of anticancer cellular vaccines targeting HER2.

| S-EPMC7563373 | biostudies-literature

Protein-polyelectrolyte interactions. The concanavalin A precipitin reaction with polyelectrolytes and polysaccharide derivatives.

Project description:1. Concanavalin A formed precipitates with polyelectrolytes such as fucoidan, RNA, heparin and bacterial lipopolysaccharides. 2. Precipitate formation also occurred between ficoll and concanavalin A. 3. Precipitate formation between concanavalin A and dextran or soluble starch was induced by the incorporation of phosphate groups into the unreactive glucans. 4. Introduction of polar groups, such as acetate, formate and phosphate, into glycogen resulted in enhanced precipitation with concanavalin A, whereas the opposite effect was noted on incorporation of hydrophobic (methyl) centres. 5. Neutral sugars and salt partially inhibited complex-formation between polyelectrolytes and concanavalin A. 6. Concanavalin A-glycogen complexes could be dissociated with 5% (w/v) trichloroacetic acid or 44% phenol-water. 7. Concanavalin A lost its glycogen-complexing ability after phenol treatment. 8. Evidence is presented for the existence of common binding sites on concanavalin A for both neutral polysaccharides and polyelectrolytes. 9. Hydrogen bonding appeared to play a major role in neutral polysaccharide-concanavalin A precipitate formation, whereas both hydrogen bonding and electrostatic forces were implicated in polyelectrolyte-concanavalin A complex-formation.

| S-EPMC1198466 | biostudies-other

Polysaccharide mycophenolate-based nanoparticles for enhanced immunosuppression and treatment of immune-mediated inflammatory diseases.

Project description:Immune-mediated inflammatory diseases (IMIDs) are characterized by immune dysregulation and severe inflammation caused by the aberrant and overactive host immunological response. Mycophenolic acid (MPA)-based immunosuppressive drugs are potential treatments for IMIDs because of their mild side-effect profile; however, their therapeutic effects are limited by the high albumin binding rate, unsatisfactory pharmacokinetics, and undefined cellular uptake selectivity. Methods: Polysaccharide mycophenolate was synthesized by conjugating MPA molecules to dextran (a typical polysaccharide widely used in drug delivery) and encapsulated extra free MPA molecules to fabricate MPA@Dex-MPA nanoparticles (NPs). The efficacy of these NPs for mediating immunosuppression and treatment of IMIDs was evaluated in imiquimod-induced psoriasis-like skin inflammation in Balb/c mice, a representative IMID model. Results: The MPA@Dex-MPA NPs exhibited high MPA loading efficiency, low albumin binding rates, and sustained MPA release, resulting in improved pharmacokinetics in vivo. Compared to free MPA, MPA@Dex-MPA NPs induced more robust therapeutic effects on IMIDs. Mechanistic studies indicated that MPA@Dex-MPA NPs were primarily distributed in dendritic cells (DCs) and significantly suppressed the overactivated DCs in vivo and in vitro. Furthermore, the recovered DCs rehabilitated the IL-23/Th17 axis function and significantly ameliorated imiquimod-induced psoriasis-like skin inflammation. Importantly, MPA@Dex-MPA NPs showed favorable safety and biocompatibility in vivo. Conclusion: Our results indicated the polysaccharide mycophenolate-based NPs to be highly promising for IMID treatment.

| S-EPMC7914372 | biostudies-literature

Enhanced humoral immune responses against T-independent antigens in Fc alpha/muR-deficient mice.

Project description:IgM is an antibody class common to all vertebrates that plays a primary role in host defenses against infection. Binding of IgM with an antigen initiates the complement cascade, accelerating cellular and humoral immune responses. However, the functional role of the Fc receptor for IgM in such immune responses remains obscure. Here we show that mice deficient in Fc alpha/muR, an Fc receptor for IgM expressed on B cells and follicular dendritic cells (FDCs), have enhanced germinal center formation and affinity maturation and memory induction of IgG3(+) B cells after immunization with T-independent (TI) antigens. Moreover, Fc alpha/muR-deficient mice show prolonged antigen retention by marginal zone B (MZB) cells and FDCs. In vitro studies demonstrate that interaction of the IgM immune complex with Fc alpha/muR partly suppress TI antigen retention by MZB cells. We further show that downregulation of complement receptor (CR)1 and CR2 or complement deprivation by in vivo injection with anti-CR1/2 antibody or cobra venom factor attenuates antigen retention by MZB cells and germinal center formation after immunization with TI antigens in Fc alpha/muR(-/-) mice. Taken together, these results suggest that Fc alpha/muR negatively regulates TI antigen retention by MZB cells and FDCs, leading to suppression of humoral immune responses against T-independent antigens.

| S-EPMC2699373 | biostudies-literature

Enhanced Intestinal Immune Response in Mice after Oral Administration of Korea Red Ginseng-Derived Polysaccharide.

Project description:(1) Background: The immunostimulatory role of the polysaccharide fraction (KRG-P) of Korea red ginseng (KRG) was studied in cells. However, its immunomodulatory activity is unknown. Therefore, we investigated the chemical properties of KRG-P and its intestinal immune responses in vitro and in vivo. (2) Methods: KRG-P monosaccharide composition and molecular weight were determined using high-performance liquid and size-exclusion chromatography systems. Immunoglobulin A (IgA) and α-defensin-1 transcript levels were measured using a SYBR Green qRT-PCR; defensin-1, Granulocyte-macrophage colony-stimulating factor (GM-CSF), and IgA protein levels were determined using Western blotting and ELISA kits. (3) Results: The molecular weight of KRG-P was estimated to be 106 kDa, and it contained neutral sugar (74.3%), uronic acid (24.6%), and proteins (1%). In vitro studies of intestinal immunomodulatory activity of KRG-P indicated that GM-CSF and IgA levels increased in Peyer's patch cells to higher levels than those obtained with KRG and induced bone marrow cell proliferation. In in vivo study, oral KRG-P administration to mice upregulated the expression of α-defensin-1 and IgA in the small intestinal tissue and that of secreted IgA in the feces. (4) Conclusions: KRG-P contributed to the modulation of intestinal immunity and maintenance of intestinal homeostasis against intestinal infection.

| S-EPMC7600159 | biostudies-literature

microRNA expression data from human corneal epithelial cells exposed to media, human tear, media + P. aeruginosa antigens, tear + P. aeruginosa antigens

Project description:Exposure to tear fluid can enhance corneal epithelial cells' ability to resist bacterial virulence mechanisms by upregulating epithelial-derived innate defense genes. The aim of this study was to further elucidate the mechanisms by which tear fluid modulates epithelial cell susceptibility to P. aeruginosa internalization and the relationship to known to be upregulated genes with tear fluid exposure. The hypothesis tested was that tear fluid effects on epithelial cells involve the induction of microRNA expression to modify innate defense gene responses to bacterial challenge.

2012-07-14 | GSE39341 | GEO

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