Fig. 5: IHC of inflammatory cells after transplantation of CIITA^+/+ or CIITA^-/- iPSC-RPE cells.

a IHC staining and bright field images of HM-22 monkey transplanted with CIITA^+/+ miPSC-RPE allografts showed inflammatory cells such as CD3⁺/CD4⁺ T cells (arrows, stained in green in the left two panels), MHC-II⁺ APCs (inside the white oval, stained in green in the third left panel) and Iba1⁺ microglia/macrophages (stained in green in the rightmost panel) in the retina and the choroid. b HM-23 monkey transplanted with CIITA^-/- miPSC-RPE allografts showed less CD3⁺/CD4⁺ T cells (stained in green in the left two panels), MHC-II⁺ APCs (stained in green in the third left panel) and Iba1⁺ microglia/macrophages (stained in green in the rightmost panel), with many pigmented cells (thick arrows), partially sheet-like, in the subretinal space. PKH (red) pre-labeling of the grafts was faint after 6 months of transplantation. DAPI (blue) was used for counter staining. INL inner nuclear layer, ONL outer nuclear layer, RPE retinal pigment epithelium. Scale bars: 20 μm. c Quantification of invading CD3⁺/CD4⁺ T cells and MHC2⁺/Iba1⁺ microglia/macrophages after transplantation of CIITA^+/+ miPSC-RPE allografts (WT; monkeys HM-22, K177, S2-4) and of CIITA^-/- miPSC-RPE allografts (KO; monkeys HM-23, HM-24, HM-25). IHC images used for quantification are in Supplementary Fig. 11 (n = 3 monkeys each). Y-axis: the frequency of iba1- or CD3-positive cells within one retinal section. Bar represents mean; P = 0.050 (iba1) and 0.083 (CD3) (Mann–Whitney U-test).