A simplified assay for the quantification of circulating activated protein C.
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.
Grupo de Investigación en Hemostasia, Trombosis, Arteriosclerosis y Biología Vascular, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Valencia, Spain. Electronic address: l.martos.marin@gmail.com.
Laura
L
Martos
Grupo de Investigación en Hemostasia, Trombosis, Arteriosclerosis y Biología Vascular, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Valencia, Spain; Unidad de Trombosis y Hemostasia, Servicio de Hematología, Hospital Universitario y Politécnico La Fe, Valencia, Spain. Electronic address: sbonanad@gmail.com.
Santiago
S
Bonanad
Grupo de Investigación en Hemostasia, Trombosis, Arteriosclerosis y Biología Vascular, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Valencia, Spain. Electronic address: ramon_luinun@gva.es.
Luis A
LA
Ramón
Grupo de Investigación en Hemostasia, Trombosis, Arteriosclerosis y Biología Vascular, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Valencia, Spain; Unidad de Trombosis y Hemostasia, Servicio de Hematología, Hospital Universitario y Politécnico La Fe, Valencia, Spain. Electronic address: cid_ana@gva.es.
Ana-Rosa
AR
Cid
Grupo de Investigación en Hemostasia, Trombosis, Arteriosclerosis y Biología Vascular, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Valencia, Spain. Electronic address: bonetestruch@gmail.com.
Elena
E
Bonet
Centro Regional de Hemodonación, Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer. IMIB, University of Murcia, Murcia, Spain. Electronic address: javier.corral@carm.es.
Javier
J
Corral
Servicio de Angiología y Cirugía Vascular, Hospital Universitario y Politécnico La Fe, Valencia, Spain. Electronic address: miralles_manher@gva.es.
Manuel
M
Miralles
Grupo de Investigación en Hemostasia, Trombosis, Arteriosclerosis y Biología Vascular, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Valencia, Spain. Electronic address: espanya_fra@gva.es.
Francisco
F
España
Grupo de Investigación en Hemostasia, Trombosis, Arteriosclerosis y Biología Vascular, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Valencia, Spain. Electronic address: navarro_silros@gva.es.
Silvia
S
Navarro
Grupo de Investigación en Hemostasia, Trombosis, Arteriosclerosis y Biología Vascular, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Valencia, Spain. Electronic address: medina_pil@gva.es.
Pilar
P
Medina
D006801:Humans; D008297:Male; D011486:Protein C / Q000032:analysis* / Q000378:metabolism*; D054556:Venous Thromboembolism / Q000097:blood*
D011486:Protein C
Activated protein C; ELISA; Protein C inhibitor; Venous thrombosis; assay