For more than eighty years vaccines have been administered along with alum - an aluminium salt known as an adjuvant - because it somehow boosted the biological agent's effect in stimulating a protection response by the recipient's immune system. A paper in Nature finally reveals how this simple chemical accomplishes this remarkable feat across the board for different vaccines.
Richard Flavell and his colleagues show that aluminium adjuvants activate Nalp3, a component of the inflammasome - a system that controls the production of specific cytokines, which are crucial molecular mediators of the immune response. Nalp3 is a member of a class of cellular receptors known as NOD-like receptors that pick up on signs of cell damage - in this case, it is the insoluble aluminium particles in the adjuvant that call in the defence after the vaccine's biological agent has raised the alarm.
As the authors point out, understanding how this widely used adjuvant acts on the immune system to enhance vaccine efficacy could help in the design of more powerful, more specific adjuvants that exploit the same biochemical pathway as alum.
Richard Flavell (Yale University School of Medicine, New Haven, CT, USA)
Abstract available online.
(C) Nature press release.
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