Immunogenicity of lipid sustained release implants containing imiquimod, α-galactosylceramide, or Quil-A

The aim of this study was to investigate and compare the immunogenicity of liposome-forming, sustained release lipid implants containing either an α-galactosylceramide (α-GalCer) analogue, imiquimod or Quil-A (QA) as adjuvants. Ovalbumin (OVA) was used as a model antigen. Groups of C57BI/6 mice were subcutaneously immunised with lipid implants containing one of the adjuvants, or inoculated with OVA in alum. The expansion of CD8⁺ and CD4⁺ transgenic T cells was analysed to assess the ability of these implants to stimulate cell-mediated immunity. In addition, the production of OVA-specific IgG antibodies was determined. QA-containing lipid implants were more efficient in the stimulation of CD8⁺ T cells and IgG antibodies than the two immunomodulators α-GalCer and imiquimod. These results suggest that, using this immunisation protocol and dose of immunomodulators, QA was superior to imiquimod and α-GalCer.