Zwirner J, Wittig A, Kremmer E, Götze O
Department of Immunology, Georg-August-University, Göttingen, Germany.
J Immunol Methods. 1998 Feb 1;211(1-2):183-90. doi: 10.1016/s0022-1759(97)00205-6.
Assessment of the overall function of the classical pathway of complement is traditionally performed by the hemolytic titration assay CH50. In the present study, we established a novel method for the quantitation of complement activity by measuring the deposition of C1q, C4, C3 and C9 on solid-phase IgM by an enzyme-linked immunosorbent assay (ELISA). Using the CH50 method as the reference, C9 deposition values displayed a sensitivity of 96.3% and a specificity of 99.4% in sera from patients with a variety of diseases. For C3, the sensitivity was 91.3% and the specificity 100%, for C4, the values were 95% and 100%, and for C1q the corresponding values were 52.9% and 98.9%. A close correlation was found between CH50 values below 30 U/ml and the deposition of C9 (r = 0.92), C3 (r = 0.91) and C4 (r = 0.92). In two patients with postinfectious glomerulonephritis normal C4 and C1q deposition was accompanied by decreased C3 and C9 deposition reflecting complement activation predominantly through the alternative pathway. In contrast, in two patients with complete C2 deficiency the deposition of C3 and C9 was undetectable together with normal C4 deposition values. Furthermore, in two patients with hereditary C1-inhibitor deficiency distinctly increased C1q deposition was accompanied by decreased C4 deposition values. In conclusion, the determination of complement deposition by ELISA represents a novel, quantitative method for the evaluation of complement activity. The measurement of C9 deposition alone or in combination with further complement proteins makes this ELISA a valuable tool for assessing the degree and level of complement consumption as well as localizing the missing protein in the case of complement deficiencies.
传统上，补体经典途径的整体功能评估是通过溶血滴定法CH50来进行的。在本研究中，我们建立了一种新的方法，通过酶联免疫吸附测定（ELISA）测量固相IgM上C1q、C4、C3和C9的沉积来定量补体活性。以CH50方法作为参考，在患有各种疾病的患者血清中，C9沉积值显示出96.3%的敏感性和99.4%的特异性。对于C3，敏感性为91.3%，特异性为100%；对于C4，值分别为95%和100%；对于C1q，相应的值为52.9%和98.9%。发现CH50值低于30 U/ml与C9（r = 0.92）、C3（r = 0.91）和C4（r = 0.92）的沉积之间存在密切相关性。在两名感染后肾小球肾炎患者中，正常的C4和C1q沉积伴随着C3和C9沉积的减少，这反映了补体主要通过替代途径激活。相反，在两名完全C2缺乏的患者中，未检测到C3和C9的沉积，而C4沉积值正常。此外，在两名遗传性C1抑制剂缺乏的患者中，C1q沉积明显增加，同时C4沉积值降低。总之，通过ELISA测定补体沉积代表了一种评估补体活性的新的定量方法。单独测量C9沉积或与其他补体蛋白联合测量，使这种ELISA成为评估补体消耗程度和水平以及在补体缺陷情况下定位缺失蛋白的有价值工具。
