NK cell regulation of T cells following LCMV infection of vaccinated and unvaccinated mice

NK cells may provide a “rheostat” function and have been shown to reduce the magnitude of antigen-specific T cell responses following infection. It remains unknown whether NK cells similarly modulate vaccine-elicited T cell responses following viral challenge. We used the LCMV clone 13 infection model to address whether NK cells regulate T cell responses in Adenovirus vector vaccinated mice following challenge. As expected, NK cell depletion in unvaccinated mice resulted in increased virus-specific CD4+ and CD8+ T cell responses and immunopathology following LCMV challenge. In contrast, NK cell depletion had minimal to no impact on antigen-specific T cell responses in mice that were vaccinated with an Ad5-GP vector prior to LCMV challenge. Moreover, NK cell depletion in vaccinated mice prior to challenge did not result in immunopathology and did not compromise protective efficacy. These data suggest that Adenovirus vaccine-elicited T cells may be less sensitive to NK cell-rheostat regulation than are T cells primed by LCMV infection. Splenic GP33-specific CD8+ T cells were isolated via FACS cell sorting at 8 days post-infection from LCMV Cl-13 infected mice. Depending on the experimental group (specifics in sample information), they may have received a prior Ad5-GP vaccine, NK-depleting antibody or isotype control antibody prior to challenge.