Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
Department of Clinical Pathology, University of Campinas, Campinas, Sao Paulo, Brazil.
J Immunol Methods. 2018 Sep;460:63-71. doi: 10.1016/j.jim.2018.06.010. Epub 2018 Jun 20.
Eculizumab (ECU) blocks complement C5 cleavage, preventing the formation of C5a and the cytolytic effects of the membrane attack complex. The presence of ECU in blood impacts routine complement tests used to monitor treatment.
Residual serum samples with normal total complement (CH50) and residual citrate plasma with normal PT/APTT were spiked with ECU at varied concentrations ranging from 25 to 600 μg/mL. In addition, seventy-one samples from patients on ECU were obtained. Artificial and patient samples were analyzed for CH50 and C5 function (Wako Diagnostics), C5 concentration (Quidel), AH50 (Wieslab ELISA) and sMAC (Quidel). ECU concentration was measured by mass spectrometry for all patients.
Complement blockage by ECU was evident in spiked artificial samples. At 25 μg/mL ECU, partial complement blockage was observed in CH50, AH50 and C5 function in serum. Complete blockage defined by undetectable AH50 (<10%) occurred at 100 μg/mL ECU. C5 concentrations remained the same regardless of ECU. sMAC results stayed around 81% of baseline in serum and 47% in citrate plasma with 50μg/mL ECU. Patient samples had ECU ranging from <5 to 1220 μg/mL. In all patients with ECU >100 μg/mL, C5 function was <29 U/mL.
The spiked sera and patient samples showed complement blockage with CH50, AH50 and C5 function assays when ECU >100 μg/mL. CH50, AH50 or C5 function assays can serve as indicators for the pharmacodynamic effects of eculizumab. Allied to ECU concentration, laboratory studies may be helpful to tailor therapy.
依库珠单抗（ECU）可阻断补体 C5 的裂解，防止 C5a 的形成和膜攻击复合物的细胞溶解作用。血液中存在 ECU 会影响用于监测治疗的常规补体检测。
用不同浓度（25 至 600μg/mL）的 ECU 对正常总补体（CH50）的剩余血清样本和正常 PT/APTT 的剩余柠檬酸盐血浆进行了加标。此外，还从接受 ECU 治疗的 71 名患者中获得了人工和患者样本。对人工和患者样本进行了 CH50 和 C5 功能（和光纯药）、C5 浓度（Quidel）、AH50（Wieslab ELISA）和 sMAC（Quidel）分析。对所有患者的 ECU 浓度进行了质谱分析。
在加标人工样本中观察到 ECU 对补体的阻断作用。在 25μg/mL 的 ECU 时，血清中的 CH50、AH50 和 C5 功能观察到部分补体阻断。在 100μg/mL 的 ECU 时，出现了完全阻断（AH50 无法检测（<10%）。无论 ECU 浓度如何，C5 浓度均保持不变。在 50μg/mL 的 ECU 时，血清中的 sMAC 结果保持在基线的 81%左右，而在柠檬酸盐血浆中为 47%。患者样本中的 ECU 浓度范围为<5 至 1220μg/mL。所有 ECU 浓度>100μg/mL 的患者的 C5 功能均<29U/mL。
当 ECU 浓度>100μg/mL 时，加标血清和患者样本的 CH50、AH50 和 C5 功能检测均显示补体阻断。CH50、AH50 或 C5 功能检测可作为依库珠单抗药效学效应的指标。与 ECU 浓度相结合，实验室研究可能有助于制定治疗方案。
