The Choice and Mechanism of Action of Adjuvants
INTRODUCTION The concept of an adjuvant, an immunity-stimulating substance, which enhances the specific immune responses, both humoral and cell-mediated, to a protein antigen was proposed by Ramon (1925). The use of the term adjuvant was used routinely until it became apparent that the amount of adjuvant included in an experimental vaccine was dose critical. If too much was administered the immune response was greatly reduced. In addition, some confusion arose with the introduction of the term ‘cancer adjuvant therapy’ which referred to drug and not vaccine therapy. The term immunopotentiator came into common use to describe microbial, chemical or synthetic substances which enhanced the immune response to an antigen. In view of the dual activity of both stimulating an elevated or depressed immune response the term ‘immunomodulating agent’ is often preferred.