Rubinstein L J, Stein K E
Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892.
J Immunol. 1988 Dec 15;141(12):4357-62.
As a means of further understanding the regulation of diversity and the development of protective immunity to the Neisseria meningitidis group C capsular polysaccharide (MCPS), we have generated and characterized, in detail, a panel of mAb against MCPS, a homopolymer of alpha(2----9)-sialic acid. Whereas the serum response to MCPS is restricted to the IgM and IgG3 isotypes, the panel of mAb includes, in addition, both IgG1 and IgG2b. Among 15 mAb of four isotypes, seven different specificities were observed based on direct binding in a fluorescence ELISA and precipitation in gel. Although all the mAb were derived from mice immunized with bacteria encapsulated with the native MCPS (strain C11), only 7 of 15 reacted with MCPS alone. Seven of 15 reacted with a natural O-acetyl-negative variant (OAc-, strain MC19) polysaccharide as well as with MCPS. Five of these reacted as much as 3 logs better with OAc- than MCPS and the other two reacted better with MCPS than OAc-. One mAb appeared to be alpha(2----9)-linkage specific as it reacted not only with MCPS and OAc-, but also with the capsular polysaccharide of Escherichia coli K92, a polymer of sialic acid linked alternately alpha(2----8) and alpha(2----9). None of the mAb reacted with the capsular polysaccharide of E. coli K1, a homopolymer of alpha(2----8)-sialic acid. In general, there was a good correlation between the ability to precipitate Ag in gel and to agglutinate bacteria; however, 3 of 15 mAb, all IgG3, did not conform to this rule in that they precipitated Ag but did not agglutinate bacteria of the relevant capsular specificity. Antibodies of both IgM and IgG isotypes and of both major specificities, MCPS-specific and those binding MCPS and OAc-, were bactericidal for strain C11, whereas only those reactive with OAc- were able to kill strain MC19.
作为进一步了解多样性调控以及针对脑膜炎奈瑟菌C群荚膜多糖（MCPS）保护性免疫发展的一种手段，我们已经详细制备并鉴定了一组针对MCPS（一种α(2→9)-唾液酸同聚物）的单克隆抗体。血清对MCPS的反应仅限于IgM和IgG3同种型，而该组单克隆抗体还包括IgG1和IgG2b。在四种同种型的15种单克隆抗体中，基于荧光ELISA中的直接结合和凝胶沉淀观察到了七种不同的特异性。尽管所有单克隆抗体均源自用天然MCPS包被的细菌（菌株C11）免疫的小鼠，但15种中只有7种仅与MCPS反应。15种中有7种与天然O-乙酰基阴性变体（OAc-，菌株MC19）多糖以及MCPS反应。其中5种与OAc-的反应比与MCPS的反应强3个对数级，另外2种与MCPS的反应比与OAc-的反应更好。一种单克隆抗体似乎是α(2→9)-连接特异性的，因为它不仅与MCPS和OAc-反应，还与大肠杆菌K92的荚膜多糖反应，后者是一种由α(2→8)和α(2→9)交替连接的唾液酸聚合物。没有一种单克隆抗体与大肠杆菌K1的荚膜多糖反应，后者是α(2→8)-唾液酸同聚物。一般来说，在凝胶中沉淀抗原的能力与凝集细菌的能力之间存在良好的相关性；然而，15种单克隆抗体中有3种（均为IgG3）不符合此规律，因为它们沉淀了抗原但未凝集具有相关荚膜特异性的细菌。IgM和IgG同种型以及两种主要特异性（MCPS特异性以及结合MCPS和OAc-的特异性）的抗体对菌株C11均具有杀菌作用，而只有那些与OAc-反应的抗体能够杀死菌株MC19。
