Evaluation of the Reactivity and Receptor Competition of HLA-G Isoforms toward Available Antibodies: Implications of Structural Characteristics of HLA-G Isoforms
Evaluation of the Reactivity and Receptor Competition of HLA-G Isoforms toward Available Antibodies: Implications of Structural Characteristics of HLA-G Isoforms
复制标题
DOI：
10.3390/ijms20235947
复制
发表时间：
2019-12-01
影响因子：
5.6
通讯作者：
Maenaka, Katsumi
中科院分区：
文献类型：
--
作者：
Furukawa, Atsushi;Meguro, Manami;Maenaka, Katsumi
人白细胞抗原（HLA）-G，由7个剪接变体组成，是一种致耐受性免疫检查点分子。通过与抑制性受体（包括白细胞Ig样受体（LILR））结合，在保护胎儿免受母体免疫应答方面发挥重要作用。最近的研究还表明，HLA-G参与癌细胞的发展和自身免疫性疾病的保护。与其充分表征的同种型HLA-G1相反，其他主要HLA-G同种型如HLA-G2对可用的抗HLA-G抗体的结合活性仅被部分理解。在这里，我们调查的结合特异性的抗HLA-G抗体通过使用表面等离子体共振。MEM-G9和G233显示出对HLA-G1的强亲和力，其解离常数在nM范围内，但未显示出对HLA-G2的亲和力。二硫键-接头HLA-G1二聚体进一步表现出显著的亲合力效应。另一方面，可用于HLA-G同种型的Western印迹的4 H84和MEM-G1可与天然HLA-G2结合，而MEM-G9和G233不能。这些结果表明HLA-G2具有部分内在无序结构。此外，MEM-G1而不是4 H84与HLA-G2的LILRB 2结合竞争。这些结果为HLA-G亚型及其检测系统的功能表征提供了新的见解。
The human leucocyte antigen (HLA)-G, which consists of seven splice variants, is a tolerogenic immune checkpoint molecule. It plays an important role in the protection of the fetus from the maternal immune response by binding to inhibitory receptors, including leukocyte Ig-like receptors (LILRs). Recent studies have also revealed that HLA-G is involved in the progression of cancer cells and the protection from autoimmune diseases. In contrast to its well characterized isoform, HLA-G1, the binding activities of other major HLA-G isoforms, such as HLA-G2, toward available anti-HLA-G antibodies are only partially understood. Here, we investigate the binding specificities of anti-HLA-G antibodies by using surface plasmon resonance. MEM-G9 and G233 showed strong affinities to HLA-G1, with a nM range for their dissociation constants, but did not show affinities to HLA-G2. The disulfide-linker HLA-G1 dimer further exhibited significant avidity effects. On the other hand, 4H84 and MEM-G1, which can be used for the Western blotting of HLA-G isoforms, can bind to native HLA-G2, while MEM-G9 and G233 cannot. These results reveal that HLA-G2 has a partially intrinsically disordered structure. Furthermore, MEM-G1, but not 4H84, competes with the LILRB2 binding of HLA-G2. These results provide novel insight into the functional characterization of HLA-G isoforms and their detection systems.