The potential of polymeric nanoparticles to increase the immunogenicity of the hapten clenbuterol

Micro-and nanoparticles prepared front the biodegradable and biocompatible polymers poly(lactide-co-glycolide) (PLGA) and polymetylmethacrylate (PMMA) have been successfully used as immunopotentiating antigen delivery systems. In our study, this approach was used to improve polyclonal antibody production to clenbuterol (CBL), a model hapten. PLGA and PMMA nanoparticles were loaded with either CBL alone or with a clenbuterol-transferrin conjugate (CBL-Tfn) and administered subcutaneously to mice. PLGA nano-particles were administered with or without the saponin adjuvant Quil A. The anti-CBL titres present in experimental sera were determined by an enzyme immunoassay (ELISA). CBL-Tfn-loaded PLGA nanoparticles co-administered with Quil A had obvious advantages immmunologically over the currently used method of raising antibodies to CBL (the positive control). The combined adjuvanticity of Quil A and PLGA nanoparticles resulted in a positive response in all four of the mice tested and in higher antibody titles than were seen in the positive control group. Furthermore, the sustained release of immunogen from the nanoparticles permitted a reduction in immunizing frequency over the 15-week study period.