Improved Stimulation of Human Dendritic Cells by Receptor Engagement with Surface-modified Microparticles

Abstract

Dendritic cells (DC) need to be stimulated before they can function to initiate immune responses. This study investigates whether microparticles loaded with antibodies specific for selected receptors expressed by DC can induce stimulation of these cells. Plain microparticles were compared with microparticles which were surface-loaded with specific antibodies for human CD40, Fc(gamma), alpha(v)beta3 and alpha(v)beta5 integrin receptors. The antibodies were either physically adsorbed or covalently linked to the microparticle surface. Anti-CD40 antibody and human IgG immobilised on the surface of microparticles induced enhanced DC maturation and activation as expressed by CD83 and CD86 upregulation. IL-12 secretion was induced at a detectable but relatively low level. Both anti-integrin antibodies (anti-alpha(v)beta3 and anti-alpha(v)beta5) induced comparable and considerable maturation of DC, but only anti-alpha(v)beta3 antibody induced significant activation of DC, whereas anti-alpha(v)beta5 did not. The stimulatory effects were most pronounced by employing microparticles with covalently linked antibodies, but were also observed to a minor extent when the antibodies were physically adsorbed to polystyrene and biodegradable poly(lactide-co-glycolide) microparticles. Engineering of microparticles by surface conjugation of specific ligands to stimulate DC may increase the effectiveness of microparticulate vaccine delivery systems.

Phagocytosis of poly(L-lysine)-graft-poly (ethylene glycol) coated microspheres by antigen presenting cells: Impact of grafting ratio and poly (ethylene glycol) chain length on cellular recognition

“…8 ͓The abbreviations used are MPS, mononuclear phagocytic system; APCs, antigen presenting cells; DCs, dendritic cells; M⌽, macrophages; PEG, poly͑ethylene glycol͒; PLL, poly-L-lysine; PLL͑x͒-g͓y͔-PEG͑z͒, copolymer of PEG ͑MW= z kDa͒ grafted to PLL ͑MW= x kDa͒ at a grafting ratio y; grafting ratio, g, number of lysine monomers divided by the number of PEG side chains; IgG, immunoglobulin G; PS, polystyrene; HEPES buffer, 10 mM 4-͑2-hydroxyethyl͒piperazine-1-ethane-sulfonic acid, pH 7.4; PBS buffer, 10 mM phosphate buffered saline, pH 7.4; RPMI medium, RPMI 1640 ͑Roswell Park Memorial Institute͒ with L-glutamine; and SSC, side scattering ͑measured by flow cytometry͒.͔ It is generally recognized that surface modifications of microparticulate antigen delivery systems with suitable peptides, proteins, oligosaccharides, or nucleic acids are of potential interest to control their first encounter with APC and could thus affect the type of immune response that will be elicited. [9][10][11][12] In order to specifically target APC, ligand mediated interactions with suitable receptors would be necessary.…”

Multiple and time-scheduled in situ DNA delivery mediated by β-cyclodextrin embedded in a polyelectrolyte multilayer

“…This technique allows the preparation of supramolecular nano-architectures (8-13) exhibiting specific properties in terms of control of cell activation (8)(9)(10)(11) and may also play a role in the development of local drug delivery systems (12). Peptides and proteins, chemically bound, adsorbed, or embedded in LBL films, have been shown to retain their biological activities (14)(15)(16). Cyclodextrins (CDs) constitute a group of cyclic oligosaccharides that have been shown to improve the bioavailability of many drugs by forming inclusion complexes with them (17).…”

“Wrapped Up” Vaccines in the Context of HIV-1 Immunotherapy

“…It has been demonstrated that PLGA particles are phagocytosed by APCs [199] and ensure prolonged antigen presentation by DCs [200]. Whereas empty PLGA particles do not influence the maturation status of DCs [201,202], DC activation can be induced, if the PLGA polymer is employed to encapsulate TLR ligands (poly I:C, MPLA) or surface loaded with anti-CD40 antibodies clear activation of DCs was observed [203][204][205]. PLA particles carrying p24 protein have been shown to induce both mucosal antibody production as well as CTL responses [206,207].…”