Oil-in-water emulsion adjuvant

Oil-in-water emulsion adjuvants are **formulations**—not individual molecular targets—that enhance the immunogenicity of co-administered vaccine antigens. The most well-known example is MF59, which consists primarily of squalene oil emulsified with surfactants to form nanodroplets. These emulsions do not act as classical therapeutic targets like receptors or enzymes; instead, they function by creating an inflammatory environment that recruits immune cells such as monocytes and dendritic cells to the injection site. This leads to increased antigen uptake and presentation to lymphocytes in draining lymph nodes. Oil-in-water emulsions promote both Th1 (cellular) and Th2 (humoral) responses depending on their composition. Their mechanism involves induction of cytokines/chemokines locally rather than direct interaction with specific molecular receptors on immune cells. They have been successfully used for decades to improve vaccine efficacy against infectious diseases such as influenza.[1][2][3][4] **Note:** "Immune system stimulation via oil-in-water emulsion adjuvant" describes a process/mechanism rather than a discrete molecular target or receptor; therefore it should not be classified as a canonical therapeutic target.[1][2]

Other names

MF59 (example of a specific oil-in-water emulsion adjuvant)Squalene-based adjuvantO/W emulsion adjuvantEmulsion vaccine adjuvant

Enhances immune response by promoting recruitment and activation of immune cells at the injection site. Increases antigen uptake by dendritic cells and other APCs. Induces local upregulation of cytokines, chemokines, and innate immunity genes.