TOTAL LYMPHOID IRRADIATION - IS THERE A ROLE IN PEDIATRIC HEART-TRANSPLANTATION

Total lymphoid irradiation (TLI) is an effective adjunct in the therap y of recurrent allograft rejection in adult patients. Between Jan. 3, 1990, and Feb. 5, 1992, TLI was used in 43 heart transplant patients 4 days to 67 months (mean, 6 months) after heart transplantation for re current allograft rejection. A mean TLI dose of 700 cGy (range, 40 to 1120 cGy-) was administered during a mean of 7 weeks with adjustment i n overall dose and duration determined in part by leukopenia, thromboc ytopenia, or both. Among patients who received TLI therapy within 1 mo nth of transplantation (n = 12), the rejection rate decreased from 1.9 episodes per patient per month before TLI to 0.1 episodes per patient per month after TLI (p < 0.001). Sixty percent of patients had no fur ther rejection episodes for 6 months after TLI. Peripheral blood monon uclear cells from two patients were specifically unreactive toward don or stimulator cells in mixed-lymphocyte cultures at 2.5 and 6 months a fter TLI. During this experience three pediatric patients (ages 10 to 17 years) received TLI at 0.5, 0.8, and 0.9 months after heart transpl antation for recurrent allograft rejection. The total TLI dosage for e ach patient was 720, 800, and 800 cGy. The rejection frequency fell fr om 1.8 episodes per patient per month before TLI to 0.1 episodes after TLI (p < 0.01). During follow-up of 6 to 25 months after TLI, no adve rse sequelae of TLI were identified. One 10-year-old patient who recei ved a course of TLI immediately before retransplantation has had no re jection episodes during 2 years of follow-up. Inferences: TLI is an ef fective adjunct for intermediate-term control of recurrent allograft r ejection in adults and also appears to be a safe adjunct in at least o lder pediatric patients. In some patients TLI is associated with the d evelopment of donor-specific tolerance.