Quantification of human C1 esterase inhibitor protein using an automated turbidimetric immunoassay

Abstract

The Optilite assay allows the automated and precise quantification of C1-INH concentrations in patient samples. It could therefore be used as a tool to aid the investigation of patients with angioedema.

Classical pathway activity C3c, C4 and C1-inhibitor protein reference intervals determination in EDTA plasma

“…As for C3c and C4, the C1INH RIs determined here for the 30-50-year age partition were close to the published values for serum samples (0.21 to 0.38 g/L in healthy adult blood donors) ( 9 ).…”

“…The inter-assay CVs calculated for routine in-house mean data from internal quality controls (low and high analyte concentrations) over six months were respectively 6.4 and 2.8% for CP50, 8.5 and 9.5% for C3c, 7.6 and 6.2% for C4, and 3.5 and 3.9% for C1INH. These CVs are in line with the manufacturer’s recommendations, the currently available imprecision specifications and the literature data - although the Optilite ® assay’s analytical performances have only been published for C3c, C4 and C1INH protein concentrations ( 9 , 10 ).…”

“…The C3c and C4 protein assays are calibrated against the international reference material ERM-DA470k. The C1INH protein assay uses a pool of human sera calibrated against an internal reference material ( 9 ). Routinely, two internal quality controls (qualified in-house pooled plasmas, used over one year) are used in parallel with each sample run.…”

“…The C1INH activity was assessed using a chromogenic assay (Technoclone GmbH, Vienna, Austria) whose diagnostic performances have already been described ( 9 ). The results are expressed as the percentage of C1INH activity vs a reference sample; a normal result corresponds to between 70% and 130%.…”

Stability study and external quality assessment scheme implementation for complement components dosage on EDTA plasma

“…Les kits de dosage des fractions C3 et C4 sont quant à eux calibrés par rapport au matériel de référence ERM-DA470k/IFCC, développé pour l'harmonisation du dosage des protéines [13]. Les performances de l'automate Optilite ® pour le dosage des fractions C3 et C4 ont déjà été décrites précédemment [14], et la validation du dosage du C1-inhibiteur a fait l'objet d'une publication récente [15]. Selon notre expérience, les coefficients de variation (CV) de répétabilité et de fidélité intermédiaire sont respectivement inférieurs à 3,0 et 5,0 % pour les 4 paramètres.…”