An Overview of Adjuvant Use

Adjuvants have been used to augment the immune response to antigens for more than 70 years. Ramon first demonstrated that it was possible to increase levels of diphtheria or tetanus antitoxin by the addition of bread crumbs, agar, tapioca, starch oil, lecithin, or saponin to the vaccines (1 ). In this chapter, an overview is provided of modern vaccine adjuvants as background for more detailed discussions of promising adjuvants in chapters to follow. After a more general discussion of adjuvants including their definition, mechanisms of action, safety, ideal characteristics, impediments to development, and preclinical and clinical regulatory issues, examples will be provided of experimental vaccine adjuvants that have entered clinical trial to enhance a variety of licensed and experimental vaccines in humans. For additional expositions on this complex subject and for a historical perspective, the reader is referred to recent textbooks on vaccine adjuvants (2 –4 ) and a selection of useful review articles published over the past 18 years (5 ,10 ).