Induction of tolerance to skin homografts in rat littermates

¹ Department of Anatomy, University College, London, England

The possibility of inducing mutual tissue tolerance between pairs of rat littermates has been studied. Following splenectomy at 2–4 days extrauterine life, saline suspensions of homogenized splenic tissue were exchanged between pairs. The total amount of splenic tissue available was suspended in 0.1 ml of saline which was injected into the peritoneal cavity. Tolerance was tested by exchanging skin grafts at the age of 6 weeks. In some litters the spleens were pooled and the resulting suspension injected into all members with a view to producing a mutually tolerant group. Exchange of splenic tissue between pairs produced complete tolerance in nearly all cases where the animals survived. In cases where the spleens had been pooled only minimal evidence of tolerance was observed. The principal difficulty in these experiments was a very high mortality which was not reduced by any of the precautions taken.