Canine small bowel transplantation. A study of the immunological responses.

A canine small bowel allograft model was used to determine the effects of radiation to the graft in modifying the immunological effects of the passenger leukocytes. When untreated allografts were transplanted, death of the recipient animals occurred at a mean of nine days. The allograft was well-preserved and showed no signs of rejection. The reasons for attributing death to graft-versus-host (GVH) disease are discussed. When allografts were treated with 150 rads prior to transplantation, allograft rejection occurred, with death of the recipient animals at a mean of 9.2 days. This was the only group in which cell-mediated immunity developed. When allografts were treated with 50 rads, prolonged survival of the recipients to a mean of 28 days was noted. It is postulated that in this group a balance was struck between the allograft rejection reaction and GVH disease, with prolongation of allograft survival.