Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya, 117997 Moscow, Russia.
Semiotik LLC, 16/10 Miklukho-Maklaya, 117997 Moscow, Russia.
Int J Mol Sci. 2020 Sep 5;21(18):6511. doi: 10.3390/ijms21186511.
The level of human natural antibodies of immunoglobulin M isotype against Le in patients with breast cancer is lower than in healthy women. The epitope specificity of these antibodies has been characterized using a printed glycan array and enzyme-linked immunosorbent assay (ELISA), the antibodies being isolated from donors' blood using Le-Sepharose (Le is Galβ1-3GlcNAcβ). The isolated antibodies recognize the disaccharide but do not bind to glycans terminated with Le, which implies the impossibility of binding to regular glycoproteins of non-malignant cells. The avidity (as dissociation constant value) of antibodies probed with a multivalent disaccharide is 10 M; the nanomolar level indicates that the concentration is sufficient for physiological binding to the cognate antigen. Testing of several breast cancer cell lines showed the strongest binding to ZR 75-1. Interestingly, only 7% of the cells were positive in a monolayer with a low density, increasing up to 96% at highest density. The enhanced interaction (instead of the expected inhibition) of antibodies with ZR 75-1 cells in the presence of Galβ1-3GlcNAcβ disaccharide, indicates that the target epitope of anti-Le antibodies is a molecular pattern with a carbohydrate constituent rather than a glycan.
乳腺癌患者免疫球蛋白 M 同种型天然人类抗体针对 Le 的水平低于健康女性。这些抗体的表位特异性已使用印刷聚糖阵列和酶联免疫吸附测定（ELISA）进行了表征，使用 Le-Sepharose（Le 是 Galβ1-3GlcNAcβ）从供体血液中分离出抗体。分离出的抗体识别二糖，但不与以 Le 结尾的糖结合，这意味着不可能与非恶性细胞的常规糖蛋白结合。用多价二糖探测的抗体的亲和力（作为解离常数值）为 10 M；纳摩尔水平表明浓度足以与同源抗原进行生理结合。对几种乳腺癌细胞系的测试表明，与 ZR 75-1 的结合最强。有趣的是，在单层低密度时只有 7%的细胞呈阳性，在最高密度时增加到 96%。在 Galβ1-3GlcNAcβ二糖存在下，与 ZR 75-1 细胞的抗体相互作用增强（而不是预期的抑制）表明抗 Le 抗体的靶表位是具有碳水化合物成分的分子模式，而不是聚糖。
