Relationship between the degree of antigen adsorption to aluminum hydroxide adjuvant in interstitial fluid and antibody production

The effect of the degree of adsorption after exposure to interstitial fluid on the immune response in mice to model vaccines containing ovalbumin, alpha casein or dephosphorylated alpha casein adsorbed to aluminum hydroxide adjuvant was studied. Ovalbumin and dephosphorylated alpha casein were adsorbed in the vaccine but were completely eluted when exposed to interstitial fluid for 4 h. The presence of aluminum hydroxide adjuvant in the vaccine produced immunopotentiation compared to a solution of the protein even though the protein desorbed rapidly upon subcutaneous administration. In contrast, alpha casein was completely adsorbed to aluminum hydroxide adjuvant in both the vaccine and upon exposure to interstitial fluid. Immunopotentiation by aluminum hydroxide adjuvant was also observed in this model vaccine compared to a solution of alpha casein. The results indicated that antigen presenting cells can take up desorbed antigen from interstitial fluid as well as antigen adsorbed to aluminum-containing adjuvants.