Phagocytosis of synthetic particulate vaccine delivery systems to program dendritic cells.

Therapeutic prospects of particulates are increasingly recognized for vaccination purposes. Compared with biologic particulates, such as live or attenuated bacterial vectors and viral vectors, synthetic particulates may be expected to ease the hurdles of quality assurance and validation in vaccine development and production and shorten the time for approval and to the market. The ability of synthetic antigen-loaded particulates to elicit strong immune responses, even with low amounts of antigen and to weakly immunogenic epitopes, is suggested to be due to their efficient cross-talk with the most potent antigen-presenting cells, such as dendritic cells. Moreover, the potential of particulates for intracellular delivery and directing intracellular trafficking of antigens has evolved as a promising opportunity to target the major histocompatibility complex I pathway. In summary, synthetic particulate vaccine delivery systems are likely to play an increasingly active role in enhancing or even enabling the immunostimulating effect of antigens upon direct interaction with the target cells.