Immunonephelometric determination of the C4b-binding protein.
A fully mechanised immunonephelometric method for the rapid and specific determination of C4b-binding protein (C4b-BP) in citrated plasma is described. The method utilizes commercially available rabbit antiserum against human C4b-BP and a nephelometer analyser. A single determination can be performed within 6 min, requiring 80 microliters sample volume. The measuring range is about 10 to 200% of normal C4b-BP. Precision is characterized by intraassay coefficients of variation between 1.5% and 2.8%, and interassay coefficients of variation between 4.0% and 4.6% for the same C4b-BP concentrations. The nephelometry of C4b-BP was correlated with electroimmunodiffusion (Laurell technique; r = 0.863, y = 0.909x+7.091, n = 79). C4b-BP concentrations (143%, 96-223%; median and 2.5th-97.5th percentile) from 83 subjects with increased inflammation markers C-reactive protein (> 10 mg/l), and fibrinogen (> 4.5 g/l) showing significantly higher C4b-BP concentrations compared to 151 obviously healthy subjects (97%, 68-141%; p < 0.001). In contrast to 81 patients with therapeutic heparinisation (90%, 60-131%) significant decreased concentrations were found in 90 subjects under oral anticoagulant therapy (OAT) in the stable state (78%, 44-125%; p < 0.001). Depending on different INR levels (< 2.5, n = 40: 71%, 63-85%; > 2.5, n = 50: 81%, 68-92%; median and 25th-75th percentile) no significant differences of C4b-BP concentrations could be measured.
Hafner
G
G
Institute of Clinical Chemistry and Laboratory Medicine, Johannes Gutenberg-University Mainz, Germany.
Ehrenthal
W
W
Zimmer
E
E
Lotz
J
J
Schlephorst
E
E
Prellwitz
W
W
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage; D002352:Carrier Proteins / Q000097:blood*; D015935:Complement C4b / Q000378:metabolism*; D003169:Complement Inactivator Proteins; D005069:Evaluation Studies as Topic; D005260:Female; D006023:Glycoproteins; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D005779:Immunodiffusion; D007249:Inflammation / Q000097:blood; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry / Q000379:methods*
D000925:Anticoagulants; D002352:Carrier Proteins; D003169:Complement Inactivator Proteins; D006023:Glycoproteins; D015935:Complement C4b; D006493:Heparin