Li Lixia, Zhou Yingtao, Bell Carol J, Earley Marie C, Hannon W Harry, Mei Joanne V
Newborn Screening Quality Assurance Program, Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA.
J Med Screen. 2006;13(2):79-84. doi: 10.1258/096914106777589623.
In response to increasing numbers of states in the US that test newborn babies for cystic fibrosis (CF), the Newborn Screening Quality Assurance Programme initiated a pilot proficiency testing programme for immunoreactive trypsinogen (IRT), the biomarker for CF. Dried blood spot specimens (DBS) were used to evaluate the performance of laboratories that screen babies for CF.
DBS were prepared from human whole blood enriched with physiologically relevant levels of IRT. Various methods of making IRT-enriched DBS were used to optimize the recovery and stability of the biomarker, including preparation of DBS from either intact or lysed red blood cells, varying the timing of IRT addition to blood before dispensing onto filter paper, adding a protease inhibitor cocktail, and treating serum with charcoal before IRT enrichment. The recovery and stability of IRT in DBS were assessed. Newborn screening laboratories were offered the opportunity to test blind-coded DBS in the pilot PT programme.
IRT was stable in the filter paper matrix when stored for one year at either -20 degrees C or 4 degrees C. Fifty percent more IRT was recovered from DBS prepared with lysed red blood cells where the IRT was added to blood just before dispensing; however, protease inhibitors did not improve IRT recovery.
IRT in the DBS matrix is stable and can be shipped worldwide under ambient conditions. Optimal IRT recovery was achieved by adjustment of DBS production practices. Laboratories receiving specimens accurately measured IRT by a variety of commercial and in-house methods.
针对美国越来越多的州对新生儿进行囊性纤维化（CF）检测的情况，新生儿筛查质量保证计划启动了一项针对免疫反应性胰蛋白酶原（IRT）（CF的生物标志物）的试点能力验证计划。干血斑样本（DBS）用于评估筛查婴儿CF的实验室的性能。
DBS由富含生理相关水平IRT的人全血制备。使用多种制备富含IRT的DBS的方法来优化生物标志物的回收率和稳定性，包括从完整或裂解的红细胞制备DBS、改变在将血液分配到滤纸上之前添加IRT的时间、添加蛋白酶抑制剂混合物以及在富集IRT之前用活性炭处理血清。评估了DBS中IRT的回收率和稳定性。为新生儿筛查实验室提供了在试点PT计划中检测盲编码DBS的机会。
当在-20℃或4℃下储存一年时，IRT在滤纸基质中是稳定的。从裂解红细胞制备的DBS中回收的IRT多50%，其中在即将分配时将IRT添加到血液中；然而，蛋白酶抑制剂并没有提高IRT的回收率。
DBS基质中的IRT是稳定的，并且可以在环境条件下运往世界各地。通过调整DBS生产方法实现了最佳的IRT回收率。接收样本的实验室通过各种商业和内部方法准确测量了IRT。
