Vein to artery allografts: experimental evidence of immunological sensitivity in rats.

Vein allografts were studied in rats using the major histocompatibility complex-incompatible DA (RTIa) and LEW (RTI1) inbred strains. Allografts from DA rats were inserted in to 22 LEW hosts, and vice versa, by interposing a 5 mm segment of donor iliolumbar vein into a defect in the host's iliac artery (1 mm in diameter), using microsurgical techniques. Grafts were left in situ for 6 weeks and were then tested for evidence of sensitization by the insertion of an allogeneic fetal heart from the donor strain into the host's foot pad. The fetal heart beat was recorded with an ECG and the time of rejection determined by the cessation of ECG activity. As controls, allogeneic donor fetal hearts were implanted into 40 host rates (20 of each strain) which had not previously received a donor vein allograft. These were monitored by ECG, as above. Control LEW host rats rejected DA fetal hearts in a mean time of 8.45 days. Control DA hosts rejected LEW fetal hearts in 8.70 days. DA hosts with LEW vein allografts did not reject donor fetal hearts significantly sooner (mean 8.33 days) than the controls. However, LEW host rats with allografted DA veins rejected subsequent DA fetal hearts in 7.18 days, which was significantly sooner than in controls (8.45 days). These data provide evidence of sensitization of the rejection response by vein allografts.