Holmberg H, Krook A, Sjögren A M
J Clin Microbiol. 1985 Nov;22(5):808-14. doi: 10.1128/jcm.22.5.808-814.1985.
The pneumococcal C polysaccharide (PnC) is species specific and believed to be a cell wall component of all capsular types. Antibodies against PnC in human sera have been demonstrated previously, but the question of whether a rise in these antibodies occurs during pneumococcal infections has not been investigated. We used an indirect enzyme-linked immunosorbent assay (ELISA) for the estimation of PnC antibodies in 124 hospital-treated patients with pneumonia. In 3 of 6 patients with pneumococcal bacteremia and in 17 of 44 patients with S. pneumoniae isolated in the blood, sputum, or nasopharynx, a significant rise in antibody levels was recorded, accounting for a sensitivity of 38.6%. Of 35 patients with pneumonia of other known or suspected etiology, 1 gave a positive result, corresponding to a specificity of 97.1%. In addition, 3 of 8 patients with PnC antigen in the sputum as the only etiological finding and 5 of 37 patients with unknown etiology gave positive results. The PnC antibodies did not seem to have any protective capacity against pneumonia caused by pneumococci. The ELISA, in which only one antigen preparation was used, was more simple than other tests in which traditional capsular antigen preparations are used. It might therefore be used as a supplemental method in the diagnosis of pneumococcal pneumonia. The problems involved in expressing serum titers obtained with the ELISA are discussed.
肺炎球菌C多糖（PnC）具有种属特异性，被认为是所有荚膜类型的细胞壁成分。此前已证实人血清中存在抗PnC抗体，但尚未研究这些抗体在肺炎球菌感染期间是否会升高。我们采用间接酶联免疫吸附测定法（ELISA）对124例住院治疗的肺炎患者的PnC抗体进行检测。在6例肺炎球菌血症患者中的3例以及44例血液、痰液或鼻咽部分离出肺炎链球菌的患者中的17例中，抗体水平显著升高，灵敏度为38.6%。在35例其他已知或疑似病因的肺炎患者中，1例检测结果呈阳性，特异性为97.1%。此外，8例痰液中仅发现PnC抗原作为唯一病因的患者中有3例以及37例病因不明的患者中有5例检测结果呈阳性。PnC抗体似乎对肺炎球菌引起的肺炎没有任何保护作用。该ELISA仅使用一种抗原制剂，比使用传统荚膜抗原制剂的其他检测方法更简单。因此，它可作为诊断肺炎球菌肺炎的补充方法。文中还讨论了用ELISA得出血清滴度所涉及的问题。
