Aluminum phosphate adjuvant (AP)

Aluminum phosphate adjuvant Overview

Aluminum phosphate adjuvant is an insoluble salt of aluminum commonly used in human and veterinary vaccines to enhance immunogenicity[1][2][4][5]. Unlike a classical pharmacological target such as a receptor or enzyme, aluminum phosphate is a particulate vaccine excipient. Mechanistically, AP stimulates the innate immune system by forming a depot at the injection site, facilitating antigen presentation and immune cell recruitment, promoting uptake of adsorbed antigen by APCs, and activating the NLRP3 inflammasome, which drives inflammatory cytokine secretion. It preferentially stimulates a Th2 (antibody) response, making it particularly suitable for vaccines targeting extracellular pathogens and toxins. AP is not a molecular target of therapeutic agents but a delivery and immune-activation component in vaccine formulations[1][2][3][4][5][6]. Additional clarification: The query refers to “Immune system stimulation via aluminum phosphate/adjuvant” as a “target molecule/receptor.” This is inaccurate: aluminum phosphate is not a molecular drug target (such as a receptor, channel, or enzyme), but an immune-stimulating excipient (adjuvant) used in vaccine formulations to promote more robust immune responses[2][4][7].

Mechanism of Action

Enhancement of immune response via the following mechanisms: Creation of an inflammatory environment promoting recruitment of antigen-presenting cells (APCs) such as dendritic cells and macrophages; Slow release of antigen at injection site (depot effect); Activation of NLRP3 inflammasome with subsequent induction of interleukin-1β (IL-1β) and IL-18; Stimulation of Th2-type immune response and B-cell activation, promoting antibody production[1][3][4][5][6]

Biological Functions

Safety Considerations