How squalene GLAdly helps generate antigen-specific T cells via antigen-carrying neutrophils and IL-18.

The mechanisms by which squalene, which in oil-and-water emulsions has been shown to be an excellent formulation for TLR agonists, enhances the magnitude and quality of adaptive immune responses are not thoroughly defined. In this issue of the European Journal of Immunology [Eur. J. Immunol. 2015. 45: 407-417], Desbien et al. show that a squalene/TLR4-based adjuvant augments antigen-specific Th1 responses in vaccinated mice through a caspase/IL-18-dependent mechanism. This commentary will discuss the authors' findings in the context of elucidating the mechanism of action of squalene as an adjuvant, and the new questions that the work generates.