HLA alloantibodies and the mechanism of the antiglobulin-augmented lymphocytotoxicity procedure
HLA alloantibodies and the mechanism of the antiglobulin-augmented lymphocytotoxicity procedure
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DOI：
10.1016/s0198-8859(97)00174-2
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发表时间：
1997-08-01
期刊：
影响因子：
2.7
通讯作者：
Rodey, GE
中科院分区：
文献类型：
--
作者：
Fuller, TC;Fuller, AA;Rodey, GE
HLA I类异体抗原表达多个表位，这些表位可以用人类HLA异体抗体（aAb）进行血清学鉴定。我们已经证明，绝大多数HLA抗血清表现出CYNAP现象（补体依赖性细胞毒性（CDC）阴性，吸附阳性），这可以通过添加抗人免疫球蛋白（Ig）轻链（AHG）试剂转化为直接CDC阳性反应性来鉴定。在本研究中，利用亲和纯化的HLA aAb、类特异性抗igh试剂和流式细胞术定量的人Clq结合测定，进一步表征了CYNAP现象的免疫化学机制以及AHG如何覆盖CYNAP。我们发现，CYNAP反应不是低亲和力aAb的结果，也通常不是由非补体固定HLA aAb引起的。我们的实验表明，只有抗人IgL AHG试剂才能持续增强CDC并覆盖CYNAP；反igh已经没有效果了。两种不同表位特异性的非竞争HLA aAb或一种aAb与ahg增强试剂结合可产生惊人的协同作用，使Clq的结合增加200%至400%。我们从这些实验和本文中详细介绍的其他实验中得出结论，IgM aAb或两个相邻的非竞争IgG HLA aAb结合到单个HLA分子的空间不同的表位上，或单特异性IgG HLA aAb与AHG结合到该HLA aAb，是有效的（二价）C1q结合和c介导的淋巴溶解起始所必需的。相反，CYNAP现象的发生通常是因为针对单个表位的单特异性HLA aAb不能影响与Clq的高亲和力，二价相互作用并激活最终导致细胞溶解的补体。(C)美国组织相容性和免疫遗传学学会，1997。Elsevier Science Inc.出版。
HLA Class I alloantigens express multiple epitopes which can be defined serologically using human HLA alloantibodies (aAb). We have shown that the vast majority of HLA antisera exhibit the CYNAP phenomenon (complement-dependent cytotoxicity (CDC) negative, adsorption positive) which can be identified by conversion to direct CDC positive reactivity with the addition of an antihuman immunoglobulin (Ig) light chain (AHG) reagent.In this study, the immunochemical mechanisms responsible for the CYNAP phenomena and how AHG overrides CYNAP have been further characterized using affinity-purified HLA aAb, class-specific anti-IgH reagents and human Clq binding assays quantified by flow cytometry. We have found that CYNAP reactions are not the result of low affinity aAb or generally caused by non-complement fixing HLA aAb. Our experiments illustrate that only anti-human IgL AHG reagents can consistently augment CDC and override CYNAP; antiIgH have not effective. Two noncompeting HLA aAb of different epitopic specificity or one aAb in conjunction with the AHG-augmenting reagent results in striking synergy with a 200 to 400% increase in binding of Clq.We conclude from these and other experiments detailed in this article that an IgM aAb or either two adjacent, noncompeting IgG HLA aAb bound to spatially distinct epitopes on a single HLA molecule or a monospecific IgG HLA aAb in concert with the AHG binding to this HLA aAb, is required for efficient (bivalent) C1q binding and initiation of C-mediated lympholysis. In contrast, the CYNAP phenomenon usually occurs because monospecific HLA aAb directed against a single epitope cannot effect high affinity, bivalent interaction with Clq and activate complement that would ultimately lead to cytolysis. (C) American Society for Histocompatibility and Immunogenetics, 1997. Published by Elsevier Science Inc.