(442a) Activation by and Processing of Polyanhydride Nanospheres by Antigen Presenting Cells

Improving vaccine efficacy is a major area of recent research. It has been shown that biodegradable polyanhydride particles possess the capacity to function both as superb adjuvants and as single dose delivery vehicles. Currently, it is unknown how polymer particles facilitate both antigen presenting cell (APC) activation and particle internalization and processing. The method by which encapsulated antigen goes from being internalized within a particle to being processed and effectively presented on the surface of APCs plays a crucial role in the initiation of an immune response. By observing how polyanhydride nanoparticles are uptaken and processed by APCs using microscopy and evaluating activation of these cells by cell surface marker expression and cytokine secretion, we can better understand the potential of these materials as vaccine delivery vehicles. In addition, polyanhydride chemistry effects on APC uptake mechanisms will provide valuable information assisting in the rational design of vaccine delivery platforms. Copolymers of 1,6-bis(p-carboxyphenoxy)hexane and sebacic acid were synthesized and fabricated into nanoparticles by anti-solvent precipitation. Murine bone-marrow derived dendritic cells (BMDCs) were differentiated and incubated with polyanhydride nanoparticles in vitro to allow for particle internalization and cellular activation. Epifluorescent microscopy was utilized to visualize particle uptake and processing by BMDCs. Flow cytometry was employed to investigate the capacity for polyanhydride nanoparticles to increase cell surface marker expression on these cells. A LUMINEX bead assay was used to measure the secretion of multiple cytokines from APCs. As polymer hydrophobicity is decreased, cell surface marker expression is enhanced, cytokine secretion is decreased and more polyanhydride nanoparticles were internalized and processed. Since cellular processing is dependent on polymer chemistry and particle size, knowledge of how these variables can be exploited to best design delivery systems that facilitate desired immune responses for a variety of vaccine candidates is highly desirable.