At all time points examined, we noted no differences in the pathologic changes in EAU between WT mice that received bone marrow from
Cx3cr1 gfp/+ donors (
Fig. 3) and those that received bone marrow from CX
3CR1-deficient donors (
Cx3cr1gfp/gfp ). At day 14, a small number of round donor-derived GFP
+ cells infiltrated the retina at the juxtapapillary region in both
Cx3cr1 gfp/+ and
Cx3cr1gfp/gfp chimeric mice (data not shown). At this time point, host CD45
low CD11b
+ microglia (GFP
−) throughout the retinal parenchyma appeared normal. The number of donor (GFP
+) cells infiltrating both the inner and the outer retina at the optic disc region increased from day 16 (
Fig. 3A) to day 21 (data not shown) and day 28 (
Fig. 3B), which concurs with previous turnover studies performed in our laboratory.
45 The infiltrating cells in the remainder of the inner retina were GFP
+ (CX
3CR1
+) CD11b
+ donor cells of monocyte origin among the CD11b
+ GFP
− host cells (
Fig. 3C). The latter group could be separated into obvious microglia-like cells and rounded CD11b
+ GFP
− cells that likely represent activated host microglia. In eyes stained with anti-CD45 (
Fig. 3D), the full extent of the cellular infiltrate (monocytic and lymphocytic) was evident with CD45
+ cells either GFP
+ (donor-derived) or GFP
− (host-derived;
Fig. 3D), implying a mixture of host microglia and donor monocytes/macrophages are involved in the early stages of EAU. At day 16 CD11b
+ Cx
3cr1
+ cells were present in the juxtapapillary region of the retinal photoreceptor cell layer (
Fig. 3E). By day 28 after EAU induction, the extent of cellular infiltrate in the photoreceptors had greatly increased (
Fig. 3F). Z-profiles illustrating the full thickness of the retinal whole mounts from the inner retina (top) to the photoreceptor layer (bottom) demonstrated a higher density of cellular infiltrate of both host cell (GFP
−) and donor cell (GFP
+) origin in the inner retinal layers (vitread aspect), whereas infiltrating cells in the retinal photoreceptors were mainly of monocytic donor-derived (GFP
+) rather than host origin (
Figs. 3F,
3G).