Immunonephelometric quantification of group-specific component protein in patients with acute liver failure

Abstract

Serum levels of group-specific component (Gc) protein are useful in evaluating the likelihood of survival in patients with acute liver failure (ALF) who may be candidates for liver transplant surgery. Most methods for quantifying Gc protein concentration are either isotopic, manual, technically demanding, and/or time consuming to perform, and thus are not well suited for routine clinical use in a hospital setting. We modified and evaluated a recently described nonisotopic, fully automated, immunonephelometric method for quantifying serum Gc protein concentration and compared it to our previous immunoblotting method. In addition, we evaluated the effect of G-actin on the immunonephelometric measurement of Gc protein. Serum samples from 20 patients with ALF and from 20 age- and sex-matched clinic patients without liver disease were quantified by both immunoblotting and immunonephelometry. We assessed the intra-assay precision, correlation, and diagnostic accuracy of these methods in discriminating between individuals with no preexisting liver disease and those with ALF. Actin in 1.3- to 4-fold excess of Gc protein levels demonstrated minimal to no interference in the quantification of Gc protein by immunonephelometry. Immunonephelometry was more precise than immunoblotting. Gc protein values by immunonephelometry were similar to those obtained by immunoblotting, and the diagnostic accuracy of Gc protein concentration by immunonephelometry was similar to that observed by immunoblotting. Immunonephelometry provides a nonisotopic, fully automated, rapid, precise, accurate, and cost-effective method for quantifying serum levels of total Gc protein that is well suited for routine use in a hospital-based clinical laboratory.

Vitamin D binding protein is a key determinant of 25-hydroxyvitamin D levels in infants and toddlers

“…Immunonephelometry was performed with a Behring Nephelometer (Behring Diagnostics Inc, Westwood, MA) as described by Wians et al [18]. Briefly, a working Gc (DBP) standard solution (400 μg/mL) was prepared by manually diluting a 1 mg/mL solution of purified DBP protein (Calbiochem, La Jolla, CA) 1:2.5 with N-Diluent (Behring Diagnostics Inc).…”

“…(3) Immunonephelometry was performed with a Behring Nephelometer (Behring Diagnostics, Inc., Westwood, MA, USA) as described by Wians and colleagues. (18) Briefly, a working Gc (DBP) standard solution (400 mg/mL) was prepared by manually diluting a 1 mg/mL solution of purified DBP protein (Calbiochem, La Jolla, CA, USA) 1:2.5 with N-Diluent (Behring Diagnostics, Inc.). The working standard solution and subjects' serum samples were assayed in duplicate with rabbit antihuman DBP antibody (Ab) (Dako, Carpinteria, CA, USA), supplementary precipitation reagent (Suppl.R.…”

Reconstitution of the actin-scavenger system after orthotopic liver transplantation for end-stage liver disease: A prospective and longitudinal study

“…Low Gc-globulin levels have been associated with the development of multiple organ failure. 12 The actin-scavenging capacity of Gc-globulin is severely stressed in conditions with extensive release of intracellular actin, e.g., fulminant hepatic failure, [13][14][15][16] septic shock, 17 or multiple trauma. 18 Serum levels of Gc-globulin may decrease dramatically (values as low as 5% of normal have been observed), and the actin complex ratio (actinbound Gc-globulin/total Gc-globulin) increases up to 80% or 90%.…”

“…18 Serum levels of Gc-globulin may decrease dramatically (values as low as 5% of normal have been observed), and the actin complex ratio (actinbound Gc-globulin/total Gc-globulin) increases up to 80% or 90%. 19 New, rapid Gc-globulin measure-ment techniques such as immunonephelometry 15 may be useful in clinical practice.…”

Effect of vitamin D–binding protein genotype on the development of asthma in children

“…Serum 25-(OH)D was measured by radioimmunoassay kit methodology (DiaSorin, Stillwater, MN). Plasma concentration of DBP was measured by immunonephelometry, using a Behring Nephelometer (Behring Diagnostics, Westwood, MA), as described by Wians et al 29 .…”