Researchers discover unexpected mode of action for vaccine adjuvant alum

The teams of Doctor Christophe Desmet and Professor Fabrice Bureau, of the Laboratory of Cellular and Molecular Physiology within the University of Liège's GIGA-Research centre, and of Professor Ken Ishii at the University of Osaka in Japan have just discovered an unexpected mode of action for the vaccine adjuvant alum. Indeed, it seems that when a vaccine containing alum is injected, contact with alum pushes certain cells of the body to release their own DNA. The presence of this DNA outside the cells, a place where it is not to be found in normal conditions, thus acts as a stimulant of the immune system and strongly boosts the response to the vaccine.

Alum, a salt of aluminium, is currently by far the most widely used vaccine adjuvant. Developed in the middle of the 20^th century, alum has largely demonstrated its effectiveness and safety of use. That it is why it is found in numerous vaccines. Tens of millions of doses of alum are thus administered each year, and each person in our Western societies has probably received alum at least once in their life. Nevertheless, alum was developed in a relatively empirical manner; the way it helps the immune system to respond to vaccines had not been properly understood up until now.

The discovery by the Belgian and Japanese researchers thus enables a better understanding of the way current vaccines work, and should help in the creation of new adjuvants for future vaccines. The response mechanisms to DNA brought to light in this study could in particular eventually allow the development of new adjuvants with extremely targeted and effective activity.

The researchers are this week publishing their results in the journal Nature Medicine.