Innate immune cells interacting with squalene-based SE adjuvant

Innate immune cells interacting with squalene-based oil-in-water emulsions (SE) represent a critical cellular interface in modern vaccinology. Squalene-based adjuvants, such as MF59 and AS03, do not target a single specific molecular receptor but instead trigger a broad 'immuno-competent' state characterized by rapid cell recruitment and activation. Upon injection, these emulsions stimulate local muscle and resident immune cells to release chemokines, which draw in monocytes, neutrophils, and dendritic cells. These recruited innate cells phagocytose the adjuvant-antigen complex and migrate to the draining lymph nodes, where they facilitate the maturation of the adaptive immune response. This interaction is essential for enhancing the magnitude and breadth of the antibody response, particularly in populations with weakened immune systems like the elderly. Despite their widespread use in influenza vaccines, the precise intracellular signaling pathways remain a subject of active research, though the NLRP3 inflammasome is known to play a significant role.

Other names

Squalene-in-water emulsion-responsive cellsMF59-interacting cellsAS03-interacting cellsInnate immune response to squalene emulsions

Squalene-based oil-in-water emulsions (SE) act as vaccine adjuvants by creating a local immunocompetent environment at the injection site. They induce the secretion of chemokines (such as CCL2, CCL3, and CXCL8), which recruit innate immune cells including monocytes, macrophages, and dendritic cells. These cells internalize the adjuvant and co-administered antigen, subsequently transporting them to draining lymph nodes to prime adaptive T and B cell responses. While a single specific receptor for squalene has not been identified, the mechanism involves the activation of the NLRP3 inflammasome and is often independent of traditional Toll-like receptor (TLR) signaling.