Alum interaction with dendritic cell membrane lipids is essential for its adjuvanticity

Alum has long been used as a vaccine adjuvant, yet the mechanisms by which it increases antigen-specific immune responses remain unclear. Flach et al. now report that alum interacts with lipids in the plasma membrane of dendritic cells, resulting in nonphagocytic uptake of antigen and increased association with CD4+ T cells. These results suggest that, at least for dendritic cells, lipids rather than proteins may sense alum and trigger downstream signaling events that lead to enhanced T cell responses.