Figure 6. Immune responses in RCS rats.. A-D: Confocal images demonstrate labeling of non-dystrophic rat retina with autoimmune sera from untreated dystrophic RCS rats that was collected at P30 and P90 (dilution 1:20). A: Strong labeling of outer and inner segments was present at P30 (arrows), B: weaker immunolabeling of ganglion cell layer and outer segments in rat retina with serum antibodies collected at P90. C: Control staining of the non-dystrophic rat retina with anti-rhodopsin mAb (R2–12N, 1:1000) that strongly immunolabeled the outer and inner segments of photoreceptors. D: No labeling of retinal cells was observed in control immunolabeling without primary antibodies. E, F: RTL220 treatment inhibits autoantibody response against interphotoreceptor retinoid binding protein (IRBP). E: The bars represent autoantibody titers against IRBP1177–1191 and β1α1 MHC polypeptide (part of RTL) in serum from P60 rats (n=5) diluted 1:100 and measured by enzyme-linked immunosorbent assay (ELISA). Note that RTL220 decreased autoantibodies against IRBP1177–1191 peptide (black bars). Also rats produced antibodies against MHC when treated with RTL101 (β1α1 chain of MHC, gray bars). Vehicle treatment-white bar. F: RTL220-treated significantly reduced autoantibody levels against IRBP1177–1191 peptide (n=6, one-way ANOVA, p=0.0076) in sera from rats at P90 measured by ELISA at 1:100 dilutions. OS - outer segments, ONL - outer nuclear layer, INL - inner nuclear layer, GCL - ganglion cell layer, AAb - autoantibodies, MHC - major histocompatibility complex.