The Specificity of Tolerance to Homografts in the Chicken

Summary Evidence has been found which indicates that tolerance to homografts in chickens is not completely individual specific (within one breed as well as across two breeds). A total of 71 embryonic chicks were injected with blood from embryonic chicks of a different breed and, 2 and 15 days after hatching, were grafted with skin from chicks other than the blood donor but of the same breed as the blood donor. A significant percentage of these chicks had grafts which survived longer than the grafts between control chicks not previously injected with blood. The possibility that the tolerance induced by blood of one chick to skin of another was due to similarity in antigenic makeup of the 2 donor chicks, since they were of the same breed, seems discounted by 2 experiments. First, it was shown that grafts among 2-week-old chicks of the same breed did not survive to any significant degree, thus indicating the genetic disparity among chicks of the breeds used. Secondly, when the nonspecific graft survived for a fairly long period, grafts between the blood and skin donor chicks often did not survive as long.