How Aluminum Helps Vaccines

A team of immunologists at Yale University has uncovered a crucial aspect of how aluminum compounds called adjuvants make some types of vaccines more effective. Their results could lead to improved vaccine formulations (Nature, DOI: 10.1038/nature06939). Named after the Latin word for aid, adjuvants (almost always aluminum hydroxide) aggregate into particles onto which vaccine antigens can adsorb. In doing so, adjuvants help vaccine antigens get the attention of immune cells before they are cleared from the body. But the specific molecular pathways that they activate have remained unknown. Now, Richard A. Flavell's group at Yale has found that aluminum hydroxide triggers a specific conglomerate of enzymes that ultimately turn on cytokines, proteins that help direct the immune system's response to pathogens. This result doesn't discount the importance of adjuvant aggregates or rule out adjuvant activation of other immune pathways, postdoctoral fellow and study coauthor Stephanie C. Eisenbarth says. "Aluminum hydroxide is probably a good adjuvant because it can do multiple things," she adds.