Development of an automated turbidimetric immunoassay for quantification of bovine serum immunoglobulin G

SUMMARY Objective To develop an automated turbidimetric immunoassay (TIA) for measurement of bovine IgG. Sample Population 24 bovine serum samples. Procedure IgG concentration was determined by use of the TIA, and results were compared with those of the radial immunodiffusion (RID) method. Variables were determined, using commercially available reagents and a clinical biochemical analyzer. For the TIA, polyclonal goat anti-bovine IgG (Fc specific) serum, bovine IgG calibrator serum, and polyethylene glycol reaction buffer were used. Sample concentrations were determined by the instrument, using the linear regression method of least squares. The accuracy of this assay was validated by referencing to a purified bovine IgG standard and by recovery of control standards. Parallelism was documented by assay linearity and serial sample dilution linearity. Interference resulting from hemolyzed samples was examined. Results The TIA method correlated positively (r = 0.9957) and significantly (P < 0.05) with the RID method, yielding a regression equation with slope of 0.78708 and y-intercept of 1.02102. Bias attributable to hemolysis was not observed. Conclusions The TIA method is automated, accurate, and precise for bovine serum IgG quantification. Clinical Relevance This assay provides sample results in approximately 10 minutes and may be used as an alternative to the manual RID method. (Am J Vet Res 1997;58:1201–1205)