Browsing by keyword "Trisaccharides"
Now showing items 1-3 of 3
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Conversion of tumors into autologous vaccines by intratumoral injection of alpha-Gal glycolipids that induce anti-Gal/alpha-Gal epitope interactionAnti-Gal is the most abundant antibody in humans, constituting 1% of immunoglobulins. Anti-Gal binds specifically alpha-gal epitopes (Galalpha1-3Galbeta1-4GlcNAc-R). Immunogenicity of autologous tumor associated antigens (TAA) is greatly increased by manipulating tumor cells to express alpha-gal epitopes and bind anti-Gal. Glycolipids with alphagal epitopes (alpha-gal glycolipids) injected into tumors insert into the tumor cell membrane. Anti-Gal binding to the multiple alpha-gal epitopes de novo presented on the tumor cells results in targeting of these cells to APC via the interaction between the Fc portion of the bound anti-Gal and Fcgamma; receptors on APC. The APC process and present immunogenic TAA peptides and thus, effectively activate tumor specific CD4+ helper T cells and CD8+ cytotoxic T cells which destroy tumor cells in micrometastases. The induced immune response is potent enough to overcome immunosuppression by Treg cells. A phase I clinical trial indicated that alpha-gal glycolipid treatment has no adverse effects. In addition to achieving destruction of micrometastases in cancer patients with advance disease, alpha-gal glycolipid treatment may be effective as neo-adjuvant immunotherapy. Injection of alpha-gal glycolipids into primary tumors few weeks prior to resection can induce a protective immune response capable of destroying micrometastases expressing autologous TAA, long after primary tumor resection.
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Immunogenicity of influenza virus vaccine is increased by anti-gal-mediated targeting to antigen-presenting cellsThis study describes a method for increasing the immunogenicity of influenza virus vaccines by exploiting the natural anti-Gal antibody to effectively target vaccines to antigen-presenting cells (APC). This method is based on enzymatic engineering of carbohydrate chains on virus envelope hemagglutinin to carry the alpha-Gal epitope (Gal alpha 1-3Gal beta 1-4GlcNAc-R). This epitope interacts with anti-Gal, the most abundant antibody in humans (1% of immunoglobulins). Influenza virus vaccine expressing alpha-Gal epitopes is opsonized in situ by anti-Gal immunoglobulin G. The Fc portion of opsonizing anti-Gal interacts with Fc gamma receptors on APC and induces effective uptake of the vaccine virus by APC. APC internalizes the opsonized virus to transport it to draining lymph nodes for stimulation of influenza virus-specific T cells, thereby eliciting a protective immune response. The efficacy of such an influenza vaccine was demonstrated in alpha 1,3galactosyltransferase (alpha 1,3GT) knockout mice, which produce anti-Gal, using the influenza virus strain A/Puerto Rico/8/34-H1N1 (PR8). Synthesis of alpha-Gal epitopes on carbohydrate chains of PR8 virus (PR8(alpha gal)) was catalyzed by recombinant alpha1,3GT, the glycosylation enzyme that synthesizes alpha-Gal epitopes in cells of nonprimate mammals. Mice immunized with PR8(alpha gal) displayed much higher numbers of PR8-specific CD8(+) and CD4(+) T cells (determined by intracellular cytokine staining and enzyme-linked immunospot assay) and produced anti-PR8 antibodies with much higher titers than mice immunized with PR8 lacking alpha-Gal epitopes. Mice immunized with PR8(alpha gal) also displayed a much higher level of protection than PR8 immunized mice after being challenged with lethal doses of live PR8 virus. We suggest that a similar method for increasing immunogenicity may be applicable to avian influenza vaccines.
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Intratumoral injection of alpha-gal glycolipids induces xenograft-like destruction and conversion of lesions into endogenous vaccinesThis study describes a novel cancer immunotherapy treatment that exploits the natural anti-Gal Ab to destroy tumor lesions and convert them into an endogenous vaccine targeted to APC via FcgammaR. Anti-Gal constitutes 1% of immunoglobulins in humans and interacts specifically with alpha-gal epitopes (Galalpha1-3Galbeta1-4GlcNAc-R). The binding of anti-Gal to alpha-gal epitopes on pig cells mediates xenograft rejection. The proposed method uses glycolipid micelles with multiple alpha-gal epitopes (alpha-gal glycolipids). These glycolipids are extracted from rabbit red cell membranes and are comprised of ceramides with carbohydrate chains containing 5-25 carbohydrates, all capped with alpha-gal epitopes. Efficacy of this treatment was demonstrated in alpha1,3-galactosyltransferase knockout mice producing anti-Gal and bearing B16 melanoma or B16/OVA producing OVA as a surrogate tumor Ag. These mice are unique among nonprimate mammals in that, similar to humans, they lack alpha-gal epitopes and can produce the anti-Gal Ab. Intratumoral injection of alpha-gal glycolipids results in local inflammation mediated by anti-Gal binding to the multiple alpha-gal epitopes and activation of complement. These glycolipids spontaneously insert into tumor cell membranes. The binding of anti-Gal to alpha-gal expressing tumor cells induces the destruction of treated lesions as in anti-Gal-mediated xenograft rejection. Anti-Gal further opsonizes tumor cells within the lesion and, thus, targets them for effective uptake by APC that transport the tumor Ags to draining lymph nodes. APC further cross-present immunogenic tumor Ag peptides and elicit a systemic anti-tumor immune response. Similar intratumoral injection of alpha-gal glycolipids in humans is likely to induce the destruction of treated lesions and elicit a protective immune response against micrometastases.
