Induction of tolerance to HGG followed by HGG readministration can facilitate the acceptance of primary cardiac allografts. (A) CBA mice were pretreated with the YTS177/HGG + HGG reactivation protocol or with YTS177 only. These mice then received transplants of B10 cardiac allografts on day 0 with or without adjunctive anti-CD8 antibody therapy. (B) Cardiac allograft survival. ○ YTS177/HGG + HGG reactivation protocol (200 μg YTS177 on days -28 and -27 and 500 μg HGG on days -27 and -1; group i: MST, 8 days, n = 5); □200 μg YTS177 on days -28 and -27 and 200 μg YTS169 on day 0 (group ii: MST, 26 days, n = 5; P < .05 versus group i); ▪ YTS177/HGG + HGG reactivation protocol plus anti-CD8 antibody day 0 (200 μg YTS177 on days -28 and -27, 500 μg HGG on days -27 and -1, and 200 μg YTS169 on day 0; group iii: MST, > 100 days, n = 4; P < .05 versus groups i and ii). (C) Histology of long-term surviving graft from group iii, ▪ (H&E). Scale bar = 100 μm. (D) Long-term surviving graft from group iii, ▪, stained with Elastin van Giessen stain to demonstrate internal elastic lamina (IEL) and outer elastic lamina (OEL). Scale bar = 100 μm.