Tambur A R, Herrera N D, Haarberg K M K, Cusick M F, Gordon R A, Leventhal J R, Friedewald J J, Glotz D
Transplant Immunology Laboratory, Northwestern University Feinberg School of Medicine, Chicago, IL.
Comprehensive Transplant Center, Northwestern University Feinberg School of Medicine, Chicago, IL.
Am J Transplant. 2015 Sep;15(9):2421-30. doi: 10.1111/ajt.13295. Epub 2015 Apr 30.
The presence of donor-specific HLA antibodies before or after transplantation may have different implications based on the antibody strength. Yet, current approaches do not provide information regarding the true antibody strength as defined by antigen-antibody dissociation rate. To assess currently available methods, we compared between neat mean fluorescence intensity (MFI) values, C1q MFI values, ethylenediaminetetraacetic acid (EDTA)-treated samples, as well as titration studies and peak MFI values of over 7000 Luminex-based single-antigen HLA antibody data points. Our results indicate that neat MFI values do not always accurately depict antibody strength. We further showed that EDTA treatment (6%) does not always remove all inhibitory factors compared with C1q or titration studies. In this study of patients presenting with multiple antibody specificities, a prozone effect was observed in 71% of the cohort (usually not affecting all antibody specificities within a single serum sample, though). Similar to titration studies, the C1q assay was able to address the issue of potential inhibition; however, its limitation is its low sensitivity and inability to detect the presence of weak antibodies. Titration studies are the only method among the approaches used in this study to provide information suggesting antigen-antibody dissociation rates and are, therefore, likely to provide better indication of true antibody strength.
移植前后供体特异性HLA抗体的存在可能因抗体强度不同而具有不同的意义。然而，目前的方法无法提供基于抗原-抗体解离速率所定义的真实抗体强度信息。为了评估当前可用的方法，我们比较了7000多个基于Luminex的单抗原HLA抗体数据点的纯平均荧光强度（MFI）值、C1q MFI值、乙二胺四乙酸（EDTA）处理的样本、滴定研究以及峰值MFI值。我们的结果表明，纯MFI值并不总是能准确描述抗体强度。我们进一步表明，与C1q或滴定研究相比，EDTA处理（6%）并不总能去除所有抑制因子。在这项针对具有多种抗体特异性患者的研究中，71%的队列中观察到前带效应（不过通常不会影响单个血清样本中的所有抗体特异性）。与滴定研究类似，C1q检测能够解决潜在抑制问题；然而，其局限性在于灵敏度低，无法检测到弱抗体的存在。滴定研究是本研究中所使用的方法中唯一能提供表明抗原-抗体解离速率信息的方法，因此，可能能更好地指示真实抗体强度。
