Fitzgerald T J
Infect Immun. 1987 Sep;55(9):2066-73. doi: 10.1128/iai.55.9.2066-2073.1987.
Both in vivo and in vitro studies have indicated that complement plays an important role in the syphilitic immune responses. Few quantitative data are available concerning activation of the classical pathway by Treponema pallidum subsp. pallidum, and no information is available on treponemal activation of the alternative pathway. Activation of both pathways was compared by using T. pallidum subsp. pallidum and the nonpathogen T. vincentii. With rabbit and human sources of complement, both organisms rapidly activated the classical pathway, as shown by hemolysis of sensitized sheep erythrocytes and by the generation of soluble C4a. With human sources of complement, both organisms also activated the alternative pathway, as shown by hemolysis of rabbit erythrocytes and by the generation of soluble C3a in the presence of magnesium ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). During incubation, organisms remained actively mobile and did not lyse, indicating that activation was a function of complement reactivity with the intact outer treponemal surface. In addition, freshly harvested T. pallidum subsp. pallidum immediately activated both pathways of complement; preincubation of organisms did not enhance complement reactivity. T. vincentii was a more potent activator of this pathway. T. pallidum subsp. pallidum contained almost four times as much surface sialic acid as T. vincentii did. When sialic acid was enzymatically removed from T. pallidum subsp. pallidum, enhanced activation of the alternative pathway was detected. It is proposed that T. pallidum subsp. pallidum retards complement-mediated damage by the alternative pathway through surface-associated sialic acid. This may be an important virulence determinant that enables these organisms to readily disseminate through the bloodstream to infect other tissues.
体内和体外研究均表明，补体在梅毒免疫反应中起重要作用。关于梅毒螺旋体亚种苍白亚种激活经典途径的定量数据很少，关于其激活替代途径的信息则全无。通过使用梅毒螺旋体亚种苍白亚种和非病原体文森特螺旋体比较了两条途径的激活情况。利用兔和人源补体，两种微生物均能迅速激活经典途径，这可通过致敏绵羊红细胞的溶血以及可溶性C4a的产生得以证明。利用人源补体，两种微生物也能激活替代途径，这可通过兔红细胞的溶血以及在乙二醇双（β-氨基乙基醚）-N，N，N'，N'-四乙酸（EGTA）存在下可溶性C3a的产生得以证明。在孵育过程中，微生物保持活跃运动状态且未裂解，这表明激活是补体与完整梅毒螺旋体外表面反应性的一种功能。此外，新鲜收获的梅毒螺旋体亚种苍白亚种能立即激活补体的两条途径；微生物的预孵育并未增强补体反应性。文森特螺旋体是该途径更有效的激活剂。梅毒螺旋体亚种苍白亚种所含的表面唾液酸几乎是文森特螺旋体的四倍。当从梅毒螺旋体亚种苍白亚种中酶法去除唾液酸时，可检测到替代途径的激活增强。有人提出，梅毒螺旋体亚种苍白亚种通过表面相关唾液酸来减缓替代途径介导的补体损伤。这可能是一个重要的毒力决定因素，使这些微生物能够轻易地通过血流传播以感染其他组织。
