Takahashi M, Takahashi S, Brade V, Nussenzweig V
J Clin Invest. 1978 Aug;62(2):349-58. doi: 10.1172/JCI109135.
In this paper we examine the role of the classical pathway in the complement-mediated solubilization of immune precipitates (CRA). Serum reagents were depleted of the alternative pathway components properdin and factor D. Both depleted reagents lack CRA although they have almost intact hemolytic activity. Also, immune complexes were not solubilized when incubated with high concentrations of the classical pathway components (C1, C4, C2, and C3. We conclude that CRA is not mediated by the classical pathway alone. Activation of the classical pathway by the immune aggregates greatly enhances CRA. The effect of the classical pathway is to deposit C3b on the antigen-antibody lattice and promote the assembly of a lattice-associated, properdin-dependent C3-convertase. Although C3, C4, and properdin were detected on complexes solubilized by serum in the presence of Ca++ and Mg++, only C3 and properdin were found on the complexes when Ca++ had been chelated by ethylene glycol-bis-(beta-aminoethyl ether), N,N'-tetraacetic acid. In both situations the aggregates were capable of converting C5 in the fluid phase. However, no C5 was found on the solubilized complexes. These findings suggest that in contrast to nascent C3b and C4b, nascent C5-9 lacks binding affinity for immune aggregates.
在本文中，我们研究了经典途径在补体介导的免疫沉淀物溶解（CRA）中的作用。血清试剂去除了替代途径成分备解素和D因子。两种去除后的试剂都缺乏CRA，尽管它们几乎具有完整的溶血活性。此外，当与高浓度的经典途径成分（C1、C4、C2和C3）一起孵育时，免疫复合物并未溶解。我们得出结论，CRA并非仅由经典途径介导。免疫聚集体对经典途径的激活极大地增强了CRA。经典途径的作用是在抗原-抗体晶格上沉积C3b，并促进与晶格相关的、备解素依赖性C3转化酶的组装。尽管在存在Ca++和Mg++的情况下，血清溶解的复合物上检测到了C3、C4和备解素，但当Ca++被乙二醇双（β-氨基乙醚）N，N'-四乙酸螯合时，复合物上仅发现了C3和备解素。在这两种情况下，聚集体都能够在液相中转化C5。然而，在溶解的复合物上未发现C5。这些发现表明，与新生的C3b和C4b相比，新生的C5-9对免疫聚集体缺乏结合亲和力。
