Molenaar E T, Voskuyl A E, Familian A, van Mierlo G J, Dijkmans B A, Hack C E
Vrije Universiteit Medical Center, Amsterdam, The Netherlands.
Arthritis Rheum. 2001 May;44(5):997-1002. doi: 10.1002/1529-0131(200105)44:5<997::AID-ANR178>3.0.CO;2-C.
Complement activation in patients with rheumatoid arthritis (RA) is considered to be triggered by immune complexes. Recently, it was shown that C-reactive protein (CRP) can activate the complement system in vivo. We therefore hypothesized that part of the complement activation in RA is due to CRP. The aim of this study was to investigate CRP-mediated complement activation in RA, and to assess its correlation with disease activity.
Complexes between CRP and the activated complement components C3d (C3d-CRP) and C4d (C4d-CRP), which reflect CRP-mediated complement activation, as well as the overall levels of activated C3 and C4 were measured in the plasma of 107 patients with active RA and 177 patients with inactive RA. Inactive RA was defined according to the American College of Rheumatology criteria for clinical remission. Disease activity was assessed by the modified Disease Activity Score (DAS28).
Plasma levels of C3d-CRP and C4d-CRP were increased in the majority of the patients, and were significantly higher in patients with active disease versus those with inactive RA (P < 0.001). In patients with active RA, the plasma concentrations of C3d-CRP and C4d-CRP correlated significantly with the DAS28 (Spearman's rho 0.61 and 0.55, respectively; P < 0.001), whereas these correlations were less pronounced in patients with inactive RA (Spearman's rho 0.28 [P < 0.001] and 0.25 [P = 0.001], respectively). Levels of activated C3 and C4 were also increased in the majority of the patients, particularly in patients with active RA.
Part of the activation of complement in RA is mediated by CRP and is correlated with disease activity. We suggest that this activation is involved in the pathogenesis of RA.
类风湿关节炎（RA）患者体内的补体激活被认为是由免疫复合物触发的。最近有研究表明，C反应蛋白（CRP）可在体内激活补体系统。因此，我们推测RA中部分补体激活是由CRP引起的。本研究旨在探讨RA中CRP介导的补体激活情况，并评估其与疾病活动度的相关性。
在107例活动期RA患者和177例非活动期RA患者的血浆中，检测反映CRP介导补体激活的CRP与活化补体成分C3d（C3d-CRP）和C4d（C4d-CRP）之间的复合物，以及活化C3和C4的总体水平。非活动期RA根据美国风湿病学会临床缓解标准定义。采用改良疾病活动评分（DAS28）评估疾病活动度。
大多数患者血浆中C3d-CRP和C4d-CRP水平升高，活动期疾病患者的水平显著高于非活动期RA患者（P < 0.001）。在活动期RA患者中，血浆C3d-CRP和C4d-CRP浓度与DAS28显著相关（Spearman相关系数分别为0.61和0.55；P < 0.001），而在非活动期RA患者中这些相关性不太明显（Spearman相关系数分别为0.28 [P < 0.001]和0.25 [P = 0.001]）。大多数患者的活化C3和C4水平也升高，尤其是活动期RA患者。
RA中部分补体激活由CRP介导，且与疾病活动度相关。我们认为这种激活参与了RA的发病机制。
