(753g) Interactions of Bare and Protein-Loaded Adjuvants with Model Lipid Raft Mixtures at Model Interfaces

Adjuvants are substances, which when added to antigens,  increase their effectiveness of vaccines in activating the immune system against foreign pathogens. Despite their prevalence, how adjuvants stimulate the immune system is not well understood. Recent work suggests that some adjuvants, specifically aluminum adjuvants, strongly interact with lipids within the cell membrane. This adjuvant-lipid interaction possibly disrupts the membrane, allowing antigen to enter the cell without the adjuvant. To better understand the interactions between cell membrane and adjuvants, we study the interaction of bare and ovalbumin (OVA)-loaded Alhydrogel^® and MF59 with model cell membrane lipids. Our results show that Alhydrogel^® reduced the domain size density as well as the number of domains while MF59 increased the domain size in model lipid mixtures containing phospholipids, cholesterol and sphingomyelin in ratios that mimic lipid raft mixtures. Adsorption of OVA to Alhydrogel^® reduced the surface pressure faster and caused greater decrease in lipid domain size and number.