Protection against Murine Cytomegalovirus Retinitis by Adoptive Transfer of Virus-Specific CD8+ T Cells

PURPOSE. Human cytomegalovirus retinitis, the most common ophthalmic infection of AIDS patients, has been modeled in BALB/c mice infected with murine cytomegalovirus by the supraciliary route. A series of depletion and adoptive transfer studies was performed to determine whether adoptive transfer of T cells protects mice from retinitis caused by murine cytomegalovirus infection after supraciliary inoculation and to determine which subset of T cells is responsible for protection. METHODS. BALB/c mice were thymectomized and T cell-depleted by injection of monoclonal antibodies to CD4, CD8, or both. Murine cytomegalovirus (9 × 10 2 plaque forming units [pfu]) was injected into the supraciliary space. Experimental animals received murine cytomegalovirus-specific T cells or subsets of T cells 2 hours before virus injection, whereas control animals received herpes simplex virus type 1-specific T cells by tail vein injection. Eight days after virus injection, retinal pathology was scored by histopathologic examination of hematoxylin and eosin-stained ocular sections. RESULTS. CD8 + T cell depletion was sufficient for development of retinitis after supraciliary injection of murine cytomegalovirus. Adoptive transfer of murine cytomegalovirus-specific T cells, but not herpes simplex virus type 1-specific T cells, provided protection from retinitis. Additionally, separation of the murine cytomegalovirus-specific T cells into CD8 + and CD4 + subsets before adoptive transfer showed that the CD8 + fraction of the adoptive T cells was responsible for protection. CONCLUSIONS. These results suggest that adoptive transfer of cytomegalovirus-specific T cells or T cell subsets might be used to treat or prevent cytomegalovirus retinitis in immunosuppressed human patients.