Immunological analysis of a cell surface antigen by a monoclonal antibody SNH-3 in oral streptococci

使用充分表征的抗sLe ^X单克隆抗体SNH-3（MAb SNH-3 ; IgM类），通过全细胞酶联免疫吸附试验和免疫电子显微镜检查，测定唾液酸化Lewis ^X（sLe^X ; Neu 5Ac α 2 -3 Gal β 1 -4（Fuc α 1 -3）GlcNAc-R）在产生感染性心内膜炎的口腔细菌上的表达。单抗SNH-3与口腔细菌-血链球菌、变形链球菌、缓症链球菌、唾液链球菌、中间链球菌、星座链球菌、咽峡炎链球菌、化脓链球菌、伴放线杆菌、腐蚀艾肯氏菌和牙龈卟啉单胞菌的全细胞有较强的反应。免疫电镜负染显示化脓性链球菌表面有大量的活性金颗粒。我们的研究结果表明，sLe^X寡糖和许多种与感染性心内膜炎相关的细胞表面抗原之间存在免疫模拟。我们提出假设，如果这些细菌逃离它们的正常栖息地，模拟sLe^X寡糖的表面成分可能与选择素家族的宿主抗原结合，这可能促进与内皮细胞的结合，从而引发导致感染性心内膜炎的事件。

The expression of sialyl-Lewis^X (sLe^X ; Neu5Ac alpha2-3 Gal beta1-4 (Fuc alpha1-3) GlcNAc-R) on oral bacteria producing infective endocarditis was determined by a whole-cell enzyme linked immuno-sorbent assay and an immuno-electron microscopy using the well-characterized anti-sLe^X monoclonal antibody SNH-3 (MAb SNH-3 ; IgM class). mAb SNH-3 reacted strongly with whole cells of oral bacteria-Streptococcus sanguis, Streptococcus mutans, Streptococcus mitis, Streptococcus salivarius, Streptococcus intermedius, Streptococcus constellatus, Streptococcus anginosus, Streptococcus pyogenes, Actinobacillus actinomycetemcomitans, Eikenella corrodens and Porphyromonas gingivalis. The negatively stained immuno-electron micrograph of Streptococcus pyogenes showed many reactive gold particles on the cell surface. Our findings demonstrated the existence of immunologic mimicry between the sLe^X oligosaccharide and cell surface antigens of many species associated with infective endocarditis. We propose the hypothesis that if these bacteria escape their normal habitats, the surface components that mimic the sLe^X oligosaccharide might bind to host antigens of the selectin family which could promote binding to endothelial cells and, consequently, initiation of the events leading to infective endocarditis.