CARDIOPULMONARY BYPASS OR PIECES OF HUMAN NON VALVED ALLOGRAFTS

本研究中检验的假设是，在小儿心脏手术期间植入人类同种异体移植物会导致受体产生抗体反应，从而加速同种异体移植物钙化和功能障碍。该方案的具体目的是确定同种异体移植是否诱导受体中的抗体应答，表现为受体中的群体反应性抗体（PRA）升高。 到目前为止，研究人员已经前瞻性地分析了9名儿童的免疫反应，年龄在2个月到10岁之间，他们需要一个非瓣膜同种异体移植物补片来缓解先天性心脏缺陷引起的狭窄。 这些患者的诊断为：主动脉弓梗阻3例;转位2例;复杂性单心室2例;肺动脉闭锁、室间隔完整和法洛四联症各1例。 在术前、术后1周、术后1个月和术后3个月分别检测每例患者血清中HLA组反应性抗体（PRA）水平。 术前和术后1周的PRA测量值可忽略不计。 然而，在一个月内，所有患者都表现出强烈的免疫反应。 根据这些初步数据，研究人员得出结论，与带瓣同种异体移植物相似，冷冻保存的非带瓣同种异体移植物诱导强烈的HLA抗体反应，该反应在移植后三个月内扩大。 这种反应代表针对HLA I类和II类抗原的抗体。 这些发现表明，即使是小块冷冻保存的非瓣膜同种异体移植物组织，包括单尖瓣肺同种异体移植物，也表现出足够的免疫原性，以诱导可能损害组织的强烈抗体反应。

The hypothesis being tested in this study is that implantation of a human allograft during pediatric cardiac surgery causes an antibody response in the recipient, which accelerates allograft calcification and dysfunction. The specific aim of this protocol is to determine if allograft implantation induces an antibody response in the recipient manifested as an elevated panel-reactive antibody (PRA) in the recipient. To date, the investigators have prospectively analyzed the immune response of nine children, ages two months to ten years, who required a non-valved allograft patch to alleviate stenosis caused by a congenital cardiac defect. The diagnoses in these patients were: aortic arch obstruction in three; transposition in two; complex single ventricle in two; and one patient each with pulmonary atresia, intact ventricular septum, and tetralogy of Fallot. Levels of HLA panel-reactive antibody (PRA) in the serum of each patient were measured prior to surgery, one week after, one month after, and three months after allograft placement. PRA measurements were negligible preoperatively and at one week after surgery. However, within one month, all patients showed a vigorous immune response. From this preliminary data, the investigators have concluded that, similar to valved allografts, cryopreserved non-valved allografts induce a strong HLA antibody response that broadens in reactivity within three months of transplant. This response represents antibody to both HLA class I and class II antigens. These findings suggest that even small pieces of cryopreserved non-valved allograft tissue, including monocusp pulmonary allografts, exhibit sufficient immunogenicity to induce a strong antibody response that could be damaging to the tissue.