A simplified assay for the quantification of circulating activated protein C

Autores de IIS La Fe

• Laura Martos Marin

  Autor

• Santiago Bonanad Boix

  Autor

• Luis Andres Ramon Nuñez

  Autor

• Ana Rosa Cid Haro

  Autor

• Elena Bonet Estruch

  Autor

• Jaime Corral Peñafiel

  Autor

• Manuel Miralles Hernández

  Autor

• Francisco España Furio

  Autor

• Silvia Navarro Rosales

  Autor

• 

  Pilar Medina Badenes

  Autor

Grupos

• Hemostasia, Trombosis, Arteriosclerosis y Biología vascular

Abstract

Available assays for circulating levels of activated protein C (APC) are either time-consuming or difficult to use in a routine laboratory, or have a detection limit above normal levels. We have developed a simplified assay that measures both the in vivo free APC and the in vivo APC complexed to PC inhibitor (PCI). We measured APC levels, with both assays, in 339 plasma samples, 165 from patients with venous thromboembolism (VTE) and 174 from healthy individuals. The mean APC level in the 339 samples was 0.038 +/- 0.010 nM, using a previous assay that measures only the in vivo APC level, and 0.041 +/- 0.010 nM with the present new assay. The coefficient of correlation between assays was r=0.954 (P<0.001). The mean APC level in VTE patients was 0.034 +/- 0.009 nM (previous assay) and 0.037 +/- 0.009 nM (new assay), significantly lower than those in controls (P<0.001). In both groups there was a significant correlation between the levels obtained by the two assays (P<0.001). These results show that both assays are equivalent, and confirm that the APC level is lower in VTE patients than in healthy individuals. Therefore, the new simplified assay, which measures the sum of circulating free APC and APC complexed to PCI, may be used to estimate the level of circulating APC, and will allow its use in routine laboratories. (C) 2016 Elsevier B.V. All rights reserved.

Keywords

• Activated protein C; Protein C inhibitor; assay; ELISA; Venous thrombosis