Spleen transplantation from mother to child induces prolonged immunotolerance to intestinal transplantation in rats.

In phase 1 eight standard pregnant Wistar rats were used. After delivery of a litter, each mother underwent splenectomy and autotransplantation of a piece of her spleen, which has been divided into eight pieces of equal size in the omentum. The weaning rats were divided into four groups (A–D). Rats in group A (N 5 18) underwent splenectomy, and each received a transplanted piece of the mother’s spleen. Group B (N 5 18) rats each received a transplanted piece of the mother’s spleen. Group C rats (N 5 21) underwent splenectomy only, and group D rats (N 5 20) underwent sham operations. All animals were anesthetized with pentobarbital (40 mg/kg IP) for surgical intervention. Neither immunosuppressive agents nor antibiotics were administered. The animals were weighed daily and underwent extirpation of the native spleen and transplanted spleen to measure the organ weight and evaluate the organ histologically and immunologically at 4 weeks or 6 months after surgery. In phase 2 another group of rats was used to evaluate the effects of combining splenectomy and splenotransplantation on tolerance to other transplants. Weaning rats were divided into four groups and prepared as in phase 1; in addition, they underwent skin transplantation from the mother to the offspring’s back, and the condition of the transplanted skin was evaluated daily and immunohistologic studies were conducted. Histological evaluation was done using hematoxylin and eosin stain.