A prospective analysis of the immunogenicity of cryopreserved nonvalved allografts used in pediatric heart surgery

Background-The purpose of this study was to prospectively determine the imm unogenicity of nonvalved allograft tissue used to repair congenital heart d efects. Methods and Results-We prospectively analyzed the immune response of ii chi ldren, 1.4 months to 10 years of age, who required nonvalved allografts to alleviate stenosis during repair of congenital heart defects. In 7 patients , pulmonary arterial grafts were used; in 3 patients, monocusp pulmonary ar tery grafts were used; and in 1 patient, a section of glutaraldehyde-preser ved allograft pericardium was used. We measured the level of HLA panel-reac tive antibody (PRA) before surgery, 1 week after, 1 month after, and 3 mont hs after surgery. PRA was determined by the antiglobulin technique and flow cytometry. HLA class I and class II antibodies measured by either techniqu e were negligible before and 1 week after surgery, Nine of Il patients (82% ) exhibited a significant immune response at I month after surgery that fur ther increased at 3 months. The measured PRA for class I antibodies with th e antiglobulin technique increased to 43+/-36% at 1 month and to 69+/-38% a t 3 months after surgery. Flow cytometry class I PRA measurements were simi lar. Class Ii PRA increased to 26+/-34% at I month and to 41+/-36% at 3 mon ths. Age negatively correlated with the degree of elevation of PRA, but nei ther allograft area nor the area indexed to patient body surface area corre lated with PRA. Conclusions-Cryopreserved nonvalved allografts induce a strong HLA antibody response in the majority of children.