9-phenanthrol enhances the generation of an CD8+ T cell response following transcutaneous immunization with imiquimod in mice

Publication date: Available online 12 August 2017
Source:Journal of Dermatological Science
Author(s): Ann-Kathrin Hartmann, Pamela Aranda Lopez, Marek Zajac, Marc Freichel, Hansjörg Schild, Markus P. Radsak, Michael Stassen
BackgroundTranscutaneous immunization (TCI) is a non-invasive vaccination strategy targeting the skin-associated lymphoid tissue. Topical application of the TLR7 agonist imiquimod as adjuvant in combination with peptide antigens activates the innate immune system and mounts cytotoxic T lymphocyte (CTL) responses.ObjectiveBased on the commercial 5% imiquimod-containing drug Aldara we aimed to develop an improved formulation with superior vaccination efficiencies. The primary target was the enhancement of mast cell activation as important key for the function of the innate immune system.MethodsWe investigated the effects of 9-phenanthrol (9-phe) on the activation of mast cells in vitro and in vivo. For TCI, we applied 0.2% 9-phe in Aldara or Aldara alone as adjuvants in combination with the MHC class I − restricted peptide SIINFEKL. To monitor vaccination, mast cell degranulation, migration of DC and frequencies of epitope-specific CTL was assessed. In a transgenic tumor model, the efficiencies of prophylactic immunization against a tumor antigen were also monitored.Results9-phe induced degranulation of mast cells in vitro and upon topical application in vivo. A mixture of 0.2% 9-phe in Aldara showed superior results regarding the migration of DC and the expansion of antigen-specific CTL. Consequently, prophylactic immunization with 0.2% 9-phe in Aldara caused enhanced protection against tumor inoculation.ConclusionOur data demonstrate that a simple modification of an adjuvant formulation can yield superior results in experimental vaccination protocols by boosting critical steps leading to the generation of an efficient CTL response.



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