ovalbumin and laminaran

It has immense potential for immunotherapy and vaccination to target antigens to antigen-presenting cells (APCs). Here we described a method for delivering whole protein antigens to APCs via carbohydrate-mediated targeting of Dectin-1, which is a C-type lectin and mainly expresses on subpopulations of dendritic cells and macrophages. Laminarin, which is a beta-1-3 glucan and a typical ligand for Dectin-1, was chemically coupled to ovalbumin (OVA). Compared to OVA alone, the conjugate was effectively recognized and ingested by CHO cells stably expressing Dectin-1 and bound to bone marrow dendritic cells (BMDCs) via Dectin-1. Laminarin modification led to significant enhancement of OVA-specific CD4(+) T-cell response. Moreover, when used to immunize mice, the conjugate enhanced the primary IgG antibody response to OVA. Taken together, our data suggest that APCs targeting based on glucan-Dectin-1 interaction is a promising approach to improve vaccines.

Topics: Animals; Antibody Formation; Antigen-Presenting Cells; Antigens; beta-Glucans; CD4-Positive T-Lymphocytes; CHO Cells; Cricetinae; Cricetulus; Dendritic Cells; Glucans; Lectins, C-Type; Membrane Proteins; Mice; Mice, Inbred C57BL; Nerve Tissue Proteins; Ovalbumin; Polysaccharides; Vaccines

The role of the opsonic receptors FcgammaR and CR3 on the release of arachidonic acid (AA) by human monocytes was studied using IgG-ovalbumin (OVA) equivalence immune complexes (IC), anti-OVA IgG bound to OVA-coupled latex beads, and C3bi-bound IC. Release of AA was produced by IC and latex-OVA beads bound to IgG, whereas binding of C3bi to IC inhibited the ability of IC to release AA. In contrast, coating of zymosan particles with C3bi enhanced AA release as compared with that produced by non-coated particles. Masking of C3bi on C3bi-bound IC by incubation with anti-C3 IgG resulted in the recovery of their ability to release AA, thereby suggesting that binding of C3b by IC reduces their flogogenic effects, whereas opsonization of microbial walls by complement may enhance their proinflammatory potential. The binding/uptake of opsonized zymosan particles was inhibited by anti-CR3 Ab and C3bi-bound IC, but not by beta-glucan, mannan, and anti-Toll-like receptor 2 Ab. These findings show that cooperative engagement of CR3 on both the lectin-like site involved in beta-glucan binding and the I-domain involved in C3bi binding, as it can be observed in the innate immune response, produces AA release, whereas the unique interaction of C3bi-bound IC with the I-domain of CR3, as it may occur in the adaptive immune response, diverts the IC lattice from a productive interaction with FcgammaR linked to AA release.

Topics: Arachidonic Acid; CD11b Antigen; Cells, Cultured; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Flow Cytometry; Glucans; Humans; Immunoblotting; Lectins; Leukocytes, Mononuclear; Macrophage-1 Antigen; Macrophages; Mannans; Monocytes; Ovalbumin; Phagocytosis; Polysaccharides; Protein Binding; Protein Structure, Tertiary; Receptors, IgG; Receptors, Immunologic; Time Factors; Zymosan