Dendritic Cell Migration Limits the Duration of CD8+ T-Cell Priming to Peripheral Viral Antigen

CD8(+) T cells (TCD8+) play a crucial role in immunity to viruses. Antiviral TCD8+ are initially activated by recognition of major histocompatibility complex (MHC) class I-peptide complexes on the surface of professional antigen-presenting cells (pAPC). Migration of pAPC from the site of infection to secondary lymphoid organs is likely required during a natural infection. Migrating pAPC can be directly infected with virus or may internalize antigen derived from virus-infected cells. The use of experimental virus infections to assess the requirement for pAPC migration in initiation of TCD8+ responses has proven difficult to interpret because injected virus can readily drain to secondary lymphoid organs without the need for cell-mediated transport. To overcome this ambiguity, we examined the generation of antigen-specific TCD8+ after immunization with recombinant adenoviruses that express antigen driven by skin-specific or ubiquitous promoters. We show that the induction of TCD8+ in response to tissue-targeted antigen is less efficient than the response to ubiquitously expressed antigen and that the resulting TCD8+ fail to clear all target cells pulsed with the antigenic peptide. This failure to prime a fully functional TCD8+ response results from a reduced period of priming to peripherally expressed antigen versus ubiquitously expressed antigen and correlated with a brief burst of pAPC migration from the skin, a requirement for induction of the response to peripheral antigen. These results indicate that a reduced duration of pAPC migration after virus infection likely reduces the amplitude of the TCD8+ response, allowing persistence of the peripheral virus.