Sjögren A M, Holme T
J Immunol Methods. 1987 Aug 24;102(1):93-100. doi: 10.1016/s0022-1759(87)80014-5.
A two-site ELISA for the detection of pneumococcal C-polysaccharide (PnC) has been developed. A monoclonal antibody directed against the phosphorylcholine residue of the PnC was used as catcher and an affinity-purified polyclonal anti-PnC rabbit antiserum for detection. Polyclonal antibodies against the PnC as well as capsular antigens were obtained by immunizing rabbits with type 1 pneumococci. Antibodies against the phosphorylcholine determinant of PnC could be removed by affinity purification. Remaining antibodies reacted in an ELISA with type 1 capsular polysaccharide as well as with PnC. Only in the fraction with the highest antibody activity against PnC, phosphorylcholine exhibited a slight inhibitory action. It is concluded that the purified antibody preparation reacted with an antigenic determinant shared by the two polysaccharides, in all probability a determinant associated with 2-acetamido-4-amino-2,4,6-trideoxygalactose which is the only monosaccharide component in common between PnC and the type 1 capsular polysaccharide. By the use of this affinity-purified antibody preparation, reactions with alpha-streptococci, occurring with non-purified serum, were abolished. The sensitivity and specificity of the test was determined using capsulated and non-capsulated pneumococci and alpha-streptococci known to cross-react with unpurified serum against the pneumococcal C-polysaccharide.
已开发出一种用于检测肺炎球菌C多糖（PnC）的双位点酶联免疫吸附测定法。一种针对PnC磷酸胆碱残基的单克隆抗体用作捕获抗体，一种亲和纯化的抗PnC兔多克隆抗血清用于检测。通过用1型肺炎球菌免疫兔子获得针对PnC以及荚膜抗原的多克隆抗体。针对PnC磷酸胆碱决定簇的抗体可通过亲和纯化去除。剩余的抗体在酶联免疫吸附测定中与1型荚膜多糖以及PnC发生反应。仅在对PnC具有最高抗体活性的组分中，磷酸胆碱表现出轻微的抑制作用。结论是，纯化的抗体制剂与两种多糖共有的抗原决定簇发生反应，很可能是与2-乙酰氨基-4-氨基-2,4,6-三脱氧半乳糖相关的决定簇，2-乙酰氨基-4-氨基-2,4,6-三脱氧半乳糖是PnC和1型荚膜多糖之间唯一共有的单糖成分。通过使用这种亲和纯化的抗体制剂，消除了与未纯化血清发生反应的α-链球菌的交叉反应。使用已知与针对肺炎球菌C多糖的未纯化血清发生交叉反应的有荚膜和无荚膜肺炎球菌以及α-链球菌来确定该试验的敏感性和特异性。
