Aluminium phosphate adjuvant (AlPO4)

Aluminium phosphate adjuvant surface refers to the physical and chemical interface of the amorphous aluminium phosphate particles used in vaccine formulations. These adjuvants are primarily employed to enhance the immunogenicity of vaccine antigens, particularly those that are weakly immunogenic on their own (Marrack et al., 2009, Nature Reviews Immunology). The surface properties, such as charge and surface area, are critical for the adsorption of antigens through electrostatic and ligand exchange mechanisms (HogenEsch, 2002, Vaccine). Biologically, the adjuvant acts by creating a depot effect for slow antigen release and by inducing a local pro-inflammatory environment that recruits and activates antigen-presenting cells (Ghimire, 2015, Vaccine). It is known to specifically trigger the NLRP3 inflammasome pathway, which promotes the secretion of pro-inflammatory cytokines like IL-1β and typically biases the immune system toward a Th2-mediated response (Kool et al., 2008, Journal of Experimental Medicine). This adjuvant is a standard component in many pediatric and adult vaccines, including those for Hepatitis B and Diphtheria (CDC, 2020, Vaccine Adjuvants).

Other names

Aluminum phosphateAdju-PhosAmorphous aluminium hydroxyphosphateColloidal aluminium phosphateAlPO4

The mechanism involves the adsorption of antigens to the adjuvant surface, the formation of an injection site depot for sustained antigen release, and the activation of the NLRP3 inflammasome, which recruits antigen-presenting cells and promotes a Th2-biased immune response (Marrack et al., 2009, Nature Reviews Immunology; Ghimire, 2015, Vaccine).