The presence and activity of dendritic cells (DC) in retina is controversial, as these cells are difficult to identify in retina due to limited markers and sparse numbers. Transgenic mice that express green fluorescent protein (GFP) on the CD11c promoter to label DC allowed the visualization and quantification of retinal DC. Two retina injury models, the optic nerve crush (ONC) and light injury, were used to study their injury response. Many GFP+ DC were tightly associated with retinal ganglion cell nerve fibers following ONC, while very few microglia (GFP-CD11b+ cells) were found in close contact. The GFP+ cells were greatly elevated in the outer plexiform layer following photic injury. All of the GFP+ DC were CD11b+, suggesting a myeloid origin. In addition, the GFP+ DC upregulated expression of MHC class II after injury, while the GFP-CD11b+ microglia did not. This study shows that DC were found in the retina and that they rapidly responded to neural injuries. We propose that they are a previously overlooked population, distinct from microglia, and may be important in the injury response.
Bibliographical noteFunding Information:
The authors thank Thien Sam and Katie Pierson for technical assistance and the Biomedical Image Processing Laboratory at the University of Minnesota for their help with confocal microscopy. We thank Drs. Walter Low, Phil Peterson, and Maxim Cheeran for critiques of the manuscript. This work was supported by the U.S. National Institutes of Health ( R01-EY011542 , R01-EY016376 to D.S.G., T32-EY07133-17 to U.L., and P30-EY011374 ), Research to Prevent Blindness, Inc., and the Minnesota Lions Clubs.
- Neuronal death
- Retinal ganglion cell