Preparation and characterization of a biodegradable microparticle antigen/cytokine delivery system

Biodegradable microparticles (MPs) were prepared to contain dinitrophenylated bovine serum albumin (DNP-BSA) and the cytokines interleukin (IL)-5 and IL-6. The conformational integrity of these MPs was examined by scanning electron microscopy. DNP-BSA was evaluated, postentrapment, by a bicinchoninic acid assay, SDS-PAGE, isoelectric focusing, Western blotting, ELISA and spectrophotometric analysis. The bioactivity of the ILs postentrapment was measured using bioassays. Ocular-topical (OT) and intraperitoneal (IP) administration of loaded MPs induced serum IgG, tear IgA and vaginal wash (VW) IgA responses which persisted up to 45 days post secondary immunization (P2o). OT and IP delivery elicited serum IgG and tear IgA responses up to 140 days post tertiary immunization (P3o). VW IgA responses persisted up to 45 days and 140 days P3o OT and IP delivery, respectively. Overall, the inclusion of cytokines in antigen containing MPs enhanced tear IgA antibody levels following OT delivery P2o, while elevated VW IgA responses occurred following IP delivery P2o and P3o. These data demonstrate that antigen/cytokine loaded MPs can potentiate long-term mucosal antibody responses at both target and distal effector sites as well as elicit circulating antibodies.