Unidad de Inmunología, IdiPAZ, Hospital Universitario La Paz, Madrid 28046, Spain; Centro de Investigación Biomédica en Red (CIBERER U754), Madrid, Spain.
Unidad de Inmunología, IdiPAZ, Hospital Universitario La Paz, Madrid 28046, Spain.
Mol Immunol. 2014 Apr;58(2):194-200. doi: 10.1016/j.molimm.2013.11.021. Epub 2013 Dec 28.
Complement factor H (FH) serum levels can be affected by the presence of immune complexes of FH with autoantibodies like in autoimmune forms of atypical haemolytic uraemic syndrome (aHUS) or with C3b in homozygous factor I (FI) deficiency. These complexes reduce the amount of free functional circulating FH. In this study we aimed to determine whether FH levels measurement is disturbed in some pathological conditions and to establish a method for quantifying free and total FH in serum. For that purpose, FH levels were measured in serum samples from aHUS patients having anti-FH autoantibodies or mutations in FH gene, in patients with homozygous FI deficiency, and in healthy controls. Two anti-FH monoclonal antibodies, OX24 and A229, recognizing different functional regions in FH, were used as capture antibodies in an ELISA assay. In the control group and in the group of patients with FH mutations, the FH levels obtained with the two monoclonal antibodies were similar. In patients with anti-FH autoantibodies or with homozygous FI deficiency, however, FH levels measured with both antibodies were significantly different. As these patients had complexes of FH with autoantibodies or C3b, we interpreted that OX24 was detecting total FH and A229 was recognising free FH. Therefore, quantification of FH in plasma using these two monoclonal antibodies provides not only total FH level but also gives an estimation of how much FH circulates free and is thus available to properly control complement activation.
补体因子 H（FH）血清水平可受到 FH 与自身抗体形成的免疫复合物的影响，如在自身免疫性非典型溶血性尿毒综合征（aHUS）或在同源性因子 I（FI）缺乏症中与 C3b 形成的免疫复合物，这些复合物会减少游离功能性循环 FH 的数量。在这项研究中，我们旨在确定 FH 水平测量是否在某些病理情况下受到干扰，并建立一种定量检测血清中游离和总 FH 的方法。为此，我们测量了具有抗 FH 自身抗体或 FH 基因突变的 aHUS 患者、纯合性 FI 缺乏症患者和健康对照者的血清样本中的 FH 水平。两种抗 FH 单克隆抗体 OX24 和 A229 识别 FH 中的不同功能区域，用作 ELISA 测定中的捕获抗体。在对照组和 FH 基因突变组中，两种单克隆抗体获得的 FH 水平相似。然而，在具有抗 FH 自身抗体或纯合性 FI 缺乏症的患者中，两种抗体测量的 FH 水平差异显著。由于这些患者的 FH 与自身抗体或 C3b 形成复合物，我们推断 OX24 检测的是总 FH，而 A229 识别的是游离 FH。因此，使用这两种单克隆抗体定量检测血浆中的 FH，不仅提供了总 FH 水平，还可以估计有多少 FH 游离循环，从而可以更好地控制补体激活。
