Clinical Application of Surface-Linked Liposomal Antigens

The potential usefulness of surface-linked liposomal antigens for application to vaccine development was investigated. During the course of this investigation, a significant difference was observed in the recognition of liposomal antigens by antigen-presenting cells (APCs) between liposomes with different lipid components, and this difference was closely correlated with the adjuvant activity of liposomes. In addition to this “quantitative” difference between liposomes with differential lipid components, a “qualitative” difference (i.e., a differential ability to induce cross-presentation) was also observed between liposomes with different lipid components. Although the precise mechanism underlying this difference is currently unclear, the significant difference in membrane mobility observed between these liposomes might affect their ability to induce cross-presentation. Thus, surface-linked liposomal antigens may be applicable for the development of vaccines with minimal allergic side effects and for a novel protocol of allergen immunotherapy. In addition, by utilizing their ability to induce cross-presentation, surface-linked liposomal antigens could be used to develop virus vaccines that induce a cytotoxic T-cell (CTL) response, as well as tumor vaccine preparations that present tumor antigens to APCs and induce effective antitumor responses. These data suggest that differential lipid components in liposomes lead to differential processing and presentation of liposomal antigens in APCs.