Class I and Class II anti-HLA antibodies after implantation of cryopreserved allograft material in pediatric patients

Objectives: Very little is known regarding the immune response to cryopreserved allograft valves and patch material used in the surgical repair of congenital heart defects. Methods: We prospectively measured the frequency of panel reactive antibodies directed against HLA class I (HLA-A, B, and C) and class II (HLA-DR/DQ) alloantigens in 24 children receiving cryopreserved allografts. We compared them with results in 11 previously reported control patients. Sixteen of the study patients underwent placement of a valved conduit (11 pulmonic, 5 aortic) between the right ventricle and pulmonary arteries, 6 underwent patch angioplasty of stenotic vessels with cryopreserved pulmonary artery, and 2 underwent placement of a pulmonary monocusp patch. Study patients had panel reactive antibodies measured before, 1 month, 3 months, and 1 year after the operation. Results: With allograft implantation, panel reactive antibodies increased from 1.9% ± 5% before the operation to 62% ± 33% at 31 ± 8 days after the operation, 92% ± 15% at 3.3 ± 0.6 months after the operation, and 85% ± 18% at 1.1 ± 0.2 years after the operation. The control group showed no change in panel reactive antibodies, with a level of 1.6% ± 1% before the operation, 3.2% ± 1% 28 ± 5 days after the operation, and 1.7% ± 1% 2.7 ± 0.3 months after the operation. Class II antibodies (anti-HLA-DR/DQ) rose to 49% ± 35% at 30 ± 8 days and 70% ± 26% at 3.3 ± 0.6 months after the operation. Conclusions: Cryopreserved allograft material induces a marked response that involves both class I and class II anti-HLA antibodies within 3 months after operation in children. This alloantibody response may represent a form of 'rejection' may have implications for those who require subsequent cardiac transplantation, and may play a role in early allograft failure.