title: CD8+ T cells circumvent immune privilege in the eye and mediate intraocular tumor rejection by a TNF-alpha-dependent mechanism.
abstract: Although intraocular tumors reside in an immune-privileged environment, T cells can circumvent immune privilege and mediate tumor rejection without inducing damage to normal ocular tissue. In this study, we used a well-characterized tumor, Ad5E1 (adenovirus type 5 early region 1), to analyze the role of CD8+ T cells in the pristine rejection of intraocular tumors. It has been previously documented that Ad5E1 tumor rejection can occur in the absence of CD8+ T cells. However, here we find that CD8+ T cells infiltrated intraocular Ad5E1 tumors in C57BL/6 mice. Surprisingly, CD8+ T cells from tumor-rejector mice could mediate intraocular tumor rejection following adoptive transfer to SCID mice. In determining the mechanisms behind CD8+ T cell-mediated tumor rejection, we discovered that antitumor CTL activity was neither observed nor necessary for rejection of the intraocular tumors. CD8+ T cells from rejector mice did not produce IFN-gamma in response to Ad5E1 tumor Ags or use FasL to mediate intraocular tumor rejection. Also, CD8+ T cells did not use perforin or TRAIL, as CD8+ T cells from perforin knockout (KO) and TRAIL KO mice conferred protection to SCID recipient mice following adoptive transfer. We discovered that CD8+ T cells used TNF-alpha to mediate tumor rejection, because Ad5E1 tumor cells were highly sensitive to TNF-alpha-induced apoptosis and CD8+ T cells from TNF-alpha KO mice did not protect SCID mice from progressive Ad5E1 tumor growth. The results indicate that CD8+ T cells circumvent immune privilege and mediate intraocular tumor rejection by a TNF-alpha-dependent manner while leaving the eye intact and vision preserved.
authors.affiliation: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
authors.forename: Dru S
authors.initials: DS
authors.lastname: Dace
authors.forename: Peter W
authors.initials: PW
authors.lastname: Chen
authors.forename: Jerry Y
authors.initials: JY
authors.lastname: Niederkorn
mesh_terms: D000260:Adenoviruses, Human / Q000276:immunology; D000818:Animals; D000867:Anterior Chamber / Q000276:immunology* / Q000473:pathology / Q000821:virology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000276:immunology; D005134:Eye Neoplasms / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control* / Q000821:virology; D006084:Graft Rejection / Q000235:genetics / Q000276:immunology* / Q000473:pathology / Q000821:virology; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D018345:Mice, Knockout; D016513:Mice, SCID; D009368:Neoplasm Transplantation / Q000276:immunology; D012513:Sarcoma, Experimental / Q000276:immunology / Q000473:pathology / Q000517:prevention & control; D014409:Tumor Necrosis Factor-alpha / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
chemical_list: D014409:Tumor Necrosis Factor-alpha