Understanding Adjuvants

Adjuvants were a much discussed topic on this second day of the conference, and it became clear that we are still far from understanding how they work. Take Alum, for example, which consists of insoluble aluminum salts. It is used in three quarters of all our childhood vaccines, according to Stephanie Eisenbarth of Yale University, one of the speakers today who studies Alum. 

Philippa Marrack, another Alum researcher from the National Jewish Medical and Research Center who spoke today, said that “Alum does practically everything, and it’s hard to pick out what is the really relevant thing these insoluble salts do.” At the same time, “we don’t know how the body detects Alum,” she added. 

But it’s important to understand how it works because once we know its targets, we might be able to find better ways to activate the targets, said Eisenbarth. What’s more, “we might be able to redesign it or modify it so that it works better,” Marrack said. “For example, about 20% of people fail [to respond to] hepatitis B vaccine, and we don’t understand why that is.” 

Today, Marrack showed evidence in mice that Alum can induce CD8 memory cells, contrary to the dogma that Alum mostly induces CD4+ T cell and B cell immune responses. These CD8 memory cells are not very good killers, but when Alum is given in combination with MPL, a detoxified form of bacterial lipopolysaccharides that is used as an adjuvant, the killing capacity of these induced CD8+ T cells can be improved.