title: CD45-positive cells of the retina and their responsiveness to in vivo and in vitro treatment with IFN-gamma or anti-CD40.
abstract: OBJECTIVE
  The ability to mount antigen-specific immune reactions in the retina demonstrates local recognition of retinal antigens. However, properties of antigen-presenting cells (APCs) of the retina are uncertain. The current study was undertaken to look for evidence of CD45(+) cells with APC potential in the retina and to examine their in situ and in vitro responses to IFN-gamma and anti-CD40, two stimuli known to upregulate activities associated with antigen presentation.
  
  
  METHODS
  Mice were pretreated with systemic or intracameral (IC) inoculations of IFN-gamma or anti-CD40. Retinas were harvested, enzymatically dissociated, positively selected with anti-CD45, and analyzed by flow cytometry with antibodies known to identify APCs.
  
  
  RESULTS
  The most common CD45(+) retinal cells were CD11b(+), F4/80(+), CD8 alpha(+), CD80(+), and major histocompatibility complex (MHC) class II(lo), a phenotype characteristic of central nervous system (CNS) microglia (MG). There was also a small population of DEC-205(+) cells and a smaller number of CD11c(+) cells, both markers of dendritic cells (DCs). IC inoculation of IFN-gamma led to an increase in the number of CD45(+) cells and a modest upregulation of MHC class II on CD11b(+) cells. IC inoculation of anti-CD40 also increased the total number of CD45(+) cells and the number of CD11b(+) cells, but increases in CD80 and MHC class II expression on CD11b(+) cells were insignificant. After anti-CD40 treatment, CD45(hi)11c(+) cells increased in number and altered their expression of CD11b.
  
  
  CONCLUSIONS
  Retinal MG were readily identified as the most numerous population. A small population of cells with perivascular cell (PVC)-like properties was found. They were CD45(hi)11c(+), some had elevated MHC class II, and they were affected by anti-CD40 treatment in vivo. No conventional DCs were found, although there was a distinct DEC-205(+) population. Overall, the effects of IFN-gamma and anti-CD40 treatment were attenuated in the retina in vivo and also on CD45(+) cells in culture, compared with the control.
authors.affiliation: Department of Ophthalmology, University of Minnesota, Minneapolis, Minnesota 55455-3007, USA. grege001@tc.umn.edu
authors.forename: Dale S
authors.initials: DS
authors.lastname: Gregerson
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D000938:Antigen-Presenting Cells / Q000187:drug effects / Q000276:immunology*; D018122:B7-1 Antigen / Q000032:analysis; D018845:CD11 Antigens / Q000032:analysis; D019013:CD40 Antigens / Q000276:immunology*; D016827:CD8 Antigens / Q000032:analysis; D005434:Flow Cytometry; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D016130:Immunophenotyping; D007371:Interferon-gamma / Q000494:pharmacology*; D017493:Leukocyte Common Antigens / Q000032:analysis*; D051379:Mice; D008805:Mice, Inbred A; D017628:Microglia / Q000166:cytology; D012160:Retina / Q000166:cytology* / Q000187:drug effects / Q000276:immunology; D015854:Up-Regulation
chemical_list: D000911:Antibodies, Monoclonal; D018122:B7-1 Antigen; D018845:CD11 Antigens; D019013:CD40 Antigens; D016827:CD8 Antigens; D000949:Histocompatibility Antigens Class II; D007371:Interferon-gamma; D017493:Leukocyte Common Antigens