Figure 2. Microglia and recruited mo-MFs are phenotypically distinguishable in the setting of whole-body irradiation and bone marrow transplantation (Rad/BMT).

(a) Whole-body Rad/BMT leads to recruitment of myeloid cells into the retina. C57BL/6 mice were whole-body irradiated then grafted with GFP⁺ donor bone marrow (Rad/GFP-BMT). Using this method, we can firmly establish GFP⁺ cells as donor-derived whereas all GFP⁻ cells (including microglia) are host-derived. After Rad/GFP-BMT, mice were rested for more than 3 months. Data is representative of 2 independent experiments. Cells were pre-gated on live CD45⁺ singlets. (b) Comprehensive phenotypic analysis reveals that microglia have a CD45^lo CD11c^lo F4/80^lo I-A/I-E⁻ profile in the whole-body Rad/GFP-BMT setting. GFP⁻ microglia were compared to extravascular GFP⁺ mo-MFs and intravascular classical Mo (IV Mo). (c) MFI indicates that the CD45^lo CD11c^lo F4/80^lo I-A/I-E⁻ profile of GFP⁻ microglia is significantly different from GFP⁺ mo-MFs. Data shown (mean ± s.d.) is a representative sample from n ≥ 4 individual samples/group. Significant differences were determined within samples by an unpaired t test (****p < 0.0001). Data is representative of 2 independent experiments.