Small bowel transplantation in rats. The effect of pretransplant donor-specific blood transfusions on various segments of small bowel grafts.

The effects of pretransplant donor-specific blood transfusion on the survival of orthotopic small bowel transplants in rats were investigated in the fully allogeneic BN (Rt1n) to WAG (Rt1u) donor-host combination. Previous studies show that in this combination DSTs lead to permanent survival of heterotopically transplanted hearts, marked prolongation of kidney grafts, and moderate prolongation of pancreas grafts but have no effect on skin grafts. Without pretreatment, total small bowel grafts (+/- 45 cm) were rejected in 12.2 +/- 1.8 days (mean +/- SD), and 10-cm segments of jejunum or ileum in 11.2 +/- 4.0 and 11.6 +/- 0.5 days, respectively. Three DSTs given on days -21, -14, and -7 before transplantation had no effect on graft survival in any of the groups tested. Total small bowel grafts were rejected in 12.8 +/- 2.5 days, and 10-cm-long segments or jejunum or ileum in 17.0 +/- 7.2 days and 11.5 +/- 2.7 days, respectively. Graft-versus-host disease, which was mild and transient, occurred in 50% of the nontreated rats engrafted with a total small bowel, in 40% of the animals transplanted with an ileum segment, and in none of the rats that received a jejunal transplant. In the DST-pretreated groups, none of the animals transplanted with a total small bowel or ileum segment and 16.6% of the animals transplanted with a jejunum segment showed clinical signs of GVHD. When DST pretreatment was combined with cyclosporine, grafts did not survive any longer than with cyclosporine treatment alone. It is concluded that DSTs ameliorate GVHD but do not prolong the survival of small bowel allografts nor act additively with cyclosporine treatment.