Chapter 10: Vaccine Adjuvants: Mechanisms of Action

Adjuvants are essential ingredients of subunit and inactivated vaccines. The adjuvants in the majority of licensed vaccines were developed empirically and their mechanisms of action are complex and remain incompletely understood. This chapter reviews how adjuvants enhance different components of both the innate and adaptive immune response, including the engagement of pattern recognition receptors, recruitment of inflammatory cells to the site of injection, kinetics of antigen transport to the lymph node and antigen presentation, lymphocyte migration, and the formation of germinal centers in draining lymph nodes. Knowledge of the ways in which current adjuvants work will help in the design and selection of appropriate adjuvants for new and improved vaccine formulations.