Hack C E, Paardekooper J, Eerenberg A J, Navis G O, Nijsten M W, Thijs L G, Nuijens J H
Central Laboratory, The Netherlands Red Cross Blood Transfusion Service, Amsterdam.
J Immunol Methods. 1988 Apr 6;108(1-2):77-84. doi: 10.1016/0022-1759(88)90405-x.
Levels of C3a in plasma are currently measured by a competitive inhibition radioimmunoassay (RIA) in which 125I-C3a is used as a tracer. In this paper, we describe a modification of this RIA: 125I-C3 instead of 125I-C3a is used. The lower limit of detection of this modified RIA is 6 ng of C3a per ml of plasma (i.e. 0.66 nmol/l). This RIA, performed with polyclonal anti-C3a antibodies coupled to a solid phase, appeared to be 30 times more sensitive compared with an RIA in which a monoclonal antibody against C3a is used. In vitro activation of the complement system in serum by aggregated IgG, zymosan, and cobra venom factor resulted in the generation of significant amounts of C3a. Assessment of the C3a levels by the modified RIA in serial plasma samples from patients who underwent cardiopulmonary bypass, yielded results very similar to those described in the literature for the established C3a-RIA. Thus, the modified C3a-RIA offers a convenient alternative for the detection of C3a in plasma samples.
目前，血浆中C3a的水平是通过竞争性抑制放射免疫测定法（RIA）来测量的，其中使用125I-C3a作为示踪剂。在本文中，我们描述了这种RIA的一种改进方法：使用125I-C3代替125I-C3a。这种改进后的RIA的检测下限为每毫升血浆6 ng C3a（即0.66 nmol/l）。这种使用与固相偶联的多克隆抗C3a抗体进行的RIA，与使用抗C3a单克隆抗体的RIA相比，灵敏度似乎高30倍。血清中的补体系统通过聚集的IgG、酵母聚糖和眼镜蛇毒因子进行体外激活，导致产生大量的C3a。通过改进后的RIA对接受体外循环的患者的系列血浆样本中的C3a水平进行评估，得到的结果与文献中描述的既定C3a-RIA的结果非常相似。因此，改进后的C3a-RIA为检测血浆样本中的C3a提供了一种方便的替代方法。
