PDF(Pubmed)
Abstract：
Antibodies are useful for detecting glycoprotein antigens, but a conventional antibody recognizes only a protein epitope rather than a glycan. Thus, glycan isoform detection generally requires time- and labor-consuming processes such as lectin affinity column chromatography followed by sandwich ELISA. We recently found antigen-antibody reactions that were inhibited by lectin binding to glycans on the glycoprotein antigen, leading to a convenient glycoform-specific assay. Indeed, Sambucus sieboldiana agglutinin (SSA) lectin, a binder to sialylα2,6galactose residue, inhibited antibody binding to α2,6-sialylated transferrin (Tf) (SSA inhibition). SSA inhibition was not observed with other glycoforms, such as periodate-treated, sialidase-treated and sialidase/galactosidase-treated Tf, suggesting that the assay was glycoform-specific. SSA inhibition was also applicable for visualizing localization of α2,6-sialylated-Tf in a liver section. This is the first immunohistochemical demonstration of glycoform localization in a tissue section. SSA inhibition was utilized for establishing ELISA to quantify α2,6-sialylated carcinoembryonic antigen (CEA), a marker for various cancers. In addition, α2,6-sialylated-CEA was visualized in a colonic adenocarcinoma section by SSA inhibition. The method would further be applicable to a simple and rapid estimation of other α2,6-sialylated glycoproteins and have a potential aid to histopathological diagnosis.
摘要：
抗体可用于检测糖蛋白抗原，但是传统的抗体只识别蛋白质表位而不是聚糖。因此，聚糖同种型检测通常需要耗时和费力的过程，例如凝集素亲和柱层析，然后夹心ELISA。我们最近发现抗原-抗体反应被凝集素与糖蛋白抗原上的聚糖结合所抑制，导致方便的糖型特异性测定。的确,接骨木凝集素（SSA）凝集素，唾液酸α2,6半乳糖残基的粘合剂，抑制抗体与α2,6-唾液酸化转铁蛋白(Tf)的结合(SSA抑制)。其他糖型未观察到SSA抑制，如高碘酸盐处理，唾液酸酶处理和唾液酸酶/半乳糖苷酶处理的Tf，表明该测定是糖型特异性的。SSA抑制也适用于可视化肝脏切片中α2,6-唾液酸化-Tf的定位。这是组织切片中糖型定位的第一个免疫组织化学证明。SSA抑制用于建立ELISA以定量α2,6-唾液酸化的癌胚抗原（CEA），各种癌症的标记。此外,通过SSA抑制在结肠腺癌切片中观察到α2,6-唾液酸化的CEA。该方法将进一步适用于其他α2,6-唾液酸化糖蛋白的简单快速评估，并对组织病理学诊断具有潜在帮助。
