Tamotsu M, Arai K, Fujita S, Hosotsubo K, Hayashi C, Miyai K, Miyano A, Kawanaka K, Takenaka M, Shimizu A
Diagn Immunol. 1984;2(2):116-21.
The breakdown products of the third component of complement in approximately 400 samples were measured by rocket immunoelectrophoresis and two-dimensional electrophoresis using the method of Brandslund et al [3]. It was confirmed that the measurement of the C3d level provides useful information on increased C3 consumption irrespective of the synthetic rate. Furthermore, three subfragments with C3d but without C3c antigenicity were distinguished, which were designated as C3d1, C3d2, and C3d3. The subfragment C3d3 which migrated to the most anodal side was a predominant component in the plasma from patients with autoimmune diseases. Little C3d3 subfragment was detected in normal plasma and in normal sera incubated in vitro for 24 hr. Even in the normal sera converted completely in vitro which contained little intact C3, only a limited amount of C3d3 was detected. In the plasma from postsurgical patients in whom activation of the complement system was considered to be in an acute phase, C3d3 was detected, but the C3d2 level was higher than the C3d3 level. In the plasma from patients with systemic lupus erythematosus having the normal C3d level, C3d3 was a major fragment. It is predicted that the preponderant presence of C3d3 in plasma could be the result of chronic continuous complement activation by immune complexes.
采用Brandslund等人[3]的方法，通过火箭免疫电泳和二维电泳对约400份样本中补体第三成分的降解产物进行了测定。结果证实，无论合成速率如何，C3d水平的测定都能为C3消耗增加提供有用信息。此外，还区分出了三个具有C3d但无C3c抗原性的亚片段，分别命名为C3d1、C3d2和C3d3。迁移至最阳极侧的亚片段C3d3是自身免疫性疾病患者血浆中的主要成分。在正常血浆和体外孵育24小时的正常血清中几乎检测不到C3d3亚片段。即使在体外完全转化且几乎不含完整C3的正常血清中，也仅检测到有限量的C3d3。在被认为补体系统激活处于急性期的术后患者血浆中检测到了C3d3，但C3d2水平高于C3d3水平。在C3d水平正常的系统性红斑狼疮患者血浆中，C3d3是主要片段。据推测，血浆中C3d3的优势存在可能是免疫复合物慢性持续激活补体的结果。
