Devriese Magali, Amaya-Ramirez Diego, Meng Tina, Miyadera Hiroko, Giraldo Lisa, Toullec Laurie, Usureau Cedric, Toutirais Olivier, Smaïl-Tabbone Malika, Lowe Dave, Taupin Jean Luc
Laboratoire D'immunologie et Histocompatibilité, Hôpital Saint Louis, Paris, France.
INSERM UMR976, Institut de Recherche Saint-Louis, Université de Paris, Paris, France.
HLA. 2025 Sep;106(3):e70386. doi: 10.1111/tan.70386.
The target of an anti-HLA antibody is an epitope on the surface of the antigen, and in particular the polymorphic eplet of its core, which contains one or a few polymorphic residues accessible to the molecule surface. The HLA Eplet Registry database references more than 550 HLA eplets thus deduced from AA sequence alignments. However, not all eplets have yet been verified and this list is not exhaustive. We performed a systematic analysis of sequence alignment of DQ antigens, to identify polymorphic amino acids so far not proposed as candidate eplets. From this, we describe and validate 3 DQB1 eplets targeted by sera of organ-transplanted patients and explore a new eplet overlapping the DQA103 and DQB103 chains. Serum antibody profiles using LABScreen, Lifecodes and a complementary DQ Luminex single antigen bead panel all showed a concordant pattern incriminating these residues. Moreover, antibodies were adsorbed and eluted using human splenic mononuclear cells and HLA-DQ transfected murine cell clones, thereby validating these four eplets. Their localisation by 3D modelling revealed uncertain accessibility of some residues implicated. The protrusion and accessibility of an eplet on the HLA surface may ultimately not always be sufficient to predict antibody binding, since the dynamic flexibility of the molecule can modify these parameters. Our strategy, combining Luminex single antigen assays, cell adsorption/elution and in silico prediction of surface exposure, altogether concur to ascertaining the realness of candidate eplets in the highly complex HLA system.
抗HLA抗体的靶标是抗原表面的表位，尤其是其核心的多态性表位，该表位包含一个或几个可及分子表面的多态性残基。HLA表位登记数据库引用了通过氨基酸序列比对推导得出的550多个HLA表位。然而，并非所有表位都已得到验证，且该列表并不详尽。我们对DQ抗原的序列比对进行了系统分析，以鉴定迄今未被提议作为候选表位的多态性氨基酸。据此，我们描述并验证了器官移植患者血清靶向的3个DQB1表位，并探索了一个与DQA103和DQB103链重叠的新表位。使用LABScreen、Lifecodes和互补的DQ Luminex单抗原微珠板检测血清抗体谱均显示出一致的模式，表明这些残基存在问题。此外，使用人脾单核细胞和HLA-DQ转染的鼠细胞克隆吸附并洗脱抗体，从而验证了这四个表位。通过三维建模确定其定位显示，一些相关残基的可及性不确定。HLA表面表位的突出和可及性最终可能并不总是足以预测抗体结合，因为分子的动态灵活性可以改变这些参数。我们的策略，结合Luminex单抗原检测、细胞吸附/洗脱和表面暴露的计算机预测，共同有助于确定高度复杂的HLA系统中候选表位的真实性。
