Cell-Derived Microparticles and Complement Activation in Preeclampsia Versus Normal Pregnancy

BackgroundInflammation plays a major role in the vascular dysfunction seen in preeclampsia, and several studies suggest involvement of the complement system.ObjectivesTo investigate whether complement activation on the surface of microparticles is increased in plasma of preeclamptic patients versus healthy pregnant controls.MethodsMicroparticles from plasma of preeclamptic (n = 10), healthy pregnant (n = 10) and healthy nonpregnant (n = 10) women were analyzed by flow cytometry for bound complement components (C1q, C4, C3) and complement activator molecules (C-reactive protein [CRP], serum amyloid P component [SAP], immunoglobulin [Ig]M, IgG). Fluid phase complement activation products and activator molecules were also determined.ResultsLevels of microparticles with bound complement components showed no increase in complement activation on the microparticle surface in preeclamptic women, in line with levels of fluid phase complement activation products. In healthy nonpregnant and pregnant women, bound CRP was associated with classical pathway activation on the microparticle surface, and in healthy pregnant women IgM and IgG molecules also contributed. In preeclamptic women, microparticles with bound SAP and those with IgG seemed to contribute to C1q binding without a clear association to further classical pathway activation. Furthermore, significantly increased levels of microparticles with bound CRP were present in preeclamptic compared with healthy pregnant women (median 178 × 106/L versus 47 × 106/L, P < 0.01), but without concomitant increases in complement activation.ConclusionsWe found no evidence of increased complement activation on the microparticle surface in preeclamptic women. Microparticles with bound CRP were significantly increased, but in contrast to healthy pregnant and nonpregnant women, this was not associated with increased classical pathway activation on the surface of the microparticles.