Is there a role of C-reactive protein in red blood cell aggregation?

IntroductionNumerous clinical studies related the plasma level of C-reactive protein (CRP) to the erythrocyte sedimentation rate (ESR) independent of the kind of disease. The molecular regulation of the process is unknown. MethodsWe performed a meta-analysis of 10 previous studies and experimentally probed for a direct action of CRP on red blood cells (RBCs) by different methods including determination of a microscopic aggregation index, Ca2+ imaging and analysis of sedimentation experiments. ResultsThe meta-analysis revealed a statistically significant correlation (Pearson coefficient of 0.37; P<0.0001), but we could not find any experimental evidence for a direct CRP-RBC interaction. Instead, we could confirm a correlation between fibrinogen level and ESR. ConclusionTherefore, we concluded that CRP and ESR cannot account for nor replace each other as a diagnostic measure. The correlation between CRP level and ESR is most probably caused by fibrinogen, because its increase coincides with elevated CRP levels.