title: Murine gammaherpesvirus-68 expands, but does not activate, CD11b+ gr-1+ splenocytes in vivo.
abstract: BACKGROUND
  Murine gammaherpesvirus 68 (HV-68) is an efficient pathogen, capable of infecting and establishing lifelong latency in rodents. While many studies have demonstrated the ability of this viral infection to modulate immune responses, a unifying mechanism for HV-68-induced subversion of a protective host response remains elusive. We questioned whether infection with HV-68 could expand a population of myeloid derived suppressor cells (MDSC) as one mechanism for altering protective immunity.
  
  
  METHODS
  Mice were infected with HV-68, with viral latency being established in these animals. At varying times post-infection, cells were isolated for detection of viral genomes, phenotyping of myeloid cell populations, and ex vivo analysis of suppressor activity of myeloid cells.
  
  
  RESULTS
  CD11b + Gr-1+ myeloid cells accumulated in the spleens, but not the bone marrow, of HV-68 infected mice. These cells were predominantly Gr-1+ Ly-6 G+, and could be found to contain viral genomes. Increased levels of serum S100A8/A9 produced during viral infection were consistent with the expansion of these CD11b + Gr-1+ myeloid cells. Despite their expansion, these cells exhibited no increased arginase 1 or iNOS activity, and did not have the ability to suppress anti-CD3 antibody activated T lymphocyte responses.
  
  
  CONCLUSIONS
  We concluded that HV-68 infection was capable of expanding a population of myeloid cells which were phenotypically similar to MDSC. However these cells were not sufficiently activated during the establishment of viral latency to actively suppress T cell responses.
authors.affiliation: Department of Biology, University of North Carolina at Charlotte, 9201 University City Blvd,, Charlotte, NC, 28223, USA. klbost@uncc.edu.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Nelson
authors.forename: Vinita S
authors.initials: VS
authors.lastname: Chauhan
authors.forename: Melanie D
authors.initials: MD
authors.lastname: Tolbert
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Bost