title: Activation of dendritic cells by microparticles containing Bacillus anthracis protective antigen.
abstract: We have carried out an in vitro investigation into the mechanism by which microencapsulation enhances the immunogenicity of recombinant protective antigen (rPA) from Bacillus anthracis. Murine bone marrow derived dendritic cells (DC) were cocultured with soluble and microencapsulated rPA and the activation status of the cells monitored using FACS. As compared with soluble rPA, it was found that coculture of DC with rPA-loaded microparticles stimulated higher levels of MHC II, CD54, CD80 and CD86 expression (p<0.05). To investigate the longevity of antigen presentation, splenocytes from naïve mice were pulsed overnight with (3)H-thymidine following 1, 3 or 6 days coculture with DC transiently exposed to soluble or microencapsulated rPA. Splenocyte proliferation was more pronounced, and continued for a more protracted period, if the 'feeder' cells were exposed to microencapsulated antigen as compared with soluble antigen or 'empty' microspheres. To this end, our findings indicate that microsphere uptake increases the surface expression of MHC and co-stimulatory molecules on DC and can facilitate prolonged presentation of antigen to T-cells, possibly by acting as an intracellular depot.
authors.affiliation: Biomedical Sciences, Dstl, Porton Down, Salisbury SP4 0JQ, UK.
authors.forename: Angie
authors.initials: A
authors.lastname: Westwood
authors.forename: Gareth D
authors.initials: GD
authors.lastname: Healey
authors.forename: E Diane
authors.initials: ED
authors.lastname: Williamson
authors.forename: Jim E
authors.initials: JE
authors.lastname: Eyles
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D015703:Antigens, CD / Q000032:analysis; D018122:B7-1 Antigen / Q000032:analysis; D051940:B7-2 Antigen; D001427:Bacterial Toxins / Q000276:immunology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis; D008562:Membrane Glycoproteins / Q000032:analysis; D051379:Mice; D008863:Microspheres; D013154:Spleen / Q000166:cytology
chemical_list: D000942:Antigens, Bacterial; D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D001427:Bacterial Toxins; C497965:Cd86 protein, mouse; D000949:Histocompatibility Antigens Class II; D008562:Membrane Glycoproteins; C030325:anthrax toxin; D018799:Intercellular Adhesion Molecule-1