Establishment and primary clinical application of competitive inhibition for measurement of augmenter of liver regeneration

The aim of the present study was to establish a quantitative method for the measurement of serum human augmenter of liver regeneration (hALR) using competitive inhibition that is applicable in the clinic. A monoclonal antibody to hALR was used as the primary antibody and the pure hALR protein was used as a standard for competition with Eu(3+)-labeled hALR (Eu(3+)-hALR) to plot a standard curve. Serum samples from 90 patients with various liver diseases due to hepatitis B virus (HBV) infection were used for a competitive reaction with Eu(3+)-hALR. A regression analysis of the results was performed using the standard curve to calculate the serum concentration of hALR. The minimum detectable value using direct competitive measurement established by Eu(3+)-hALR was 1 ng/ml, with a positive linear correlation within the range of 200 ng/ml. In the sera of the 90 patients, the hALR level in the severe hepatitis group was the highest, followed by that in the acute hepatitis group. The serum hALR levels in the cirrhosis and chronic hepatitis groups were significantly higher compared with those in the normal control groups (P<0.01). The direct competitive measurement method of serum hALR established in the present study has high sensitivity, specificity, stability and reliability, meets clinical requirements and may be used as potential index in clinical tests.