A useful ELISA system for human liver-type arginase, and its utility in diagnosis of liver diseases.
OBJECTIVE
To develop a new ELISA system for liver-type arginase using monoclonal antibodies against the enzyme, and to verify the utility of the arginase in diagnosis of hepatic disorders.


METHODS
We have developed an enzyme-linked immunosorbent assay (ELISA), using two kinds of monoclonal antibodies (Mo6G3 and Mo9C5) for human liver-type arginase as the first and second antibodies respectively. We have also developed a new method to eliminate the influence of erythrocyte-derived arginase contamination in hemolytic samples. This ELISA was applied to specimens received from patients with acute and chronic hepatic disease and also patients who had undergone partial hepatectomy.


RESULTS
This assay is sensitive and reproducible for the measurement of liver-type arginase in the sera of patients with liver dysfunction, and enabled us to detect enzyme concentrations as low as 27 pmol/L without any processing of the samples. The assay showed within-run coefficients of variation (CV) ranging from 1.9 to 4.1% and between-day CV from 3.6 to 5.1% for arginase concentrations varying from 57.1 to 1200 pmol/L. The recovery was 113% (mean) with a range of 96 to 129%. These antibodies reacted strongly with both recombinant and native liver-type arginases, while, to some extent, with erythrocyte-derived arginase. Correction for erythrocyte-derived arginase contamination in hemolytic samples was, however, easily made by assaying peroxidase-like activity of hemoglobin. From the view of a limited localization of arginase in the liver, the marked increase of the enzyme in serum reflects initiation of liver injury, while the rapid decrease reflects termination of the damage. Such quick normalization in circulating liver-type arginase indicated another merit of the enzyme in diagnosis of liver diseases.


CONCLUSIONS
The changes in circulating liver-type arginase level could be helpful not only in the diagnosis of liver diseases but also subsequent treatment of the patients with liver damage.
Ikemoto
M
M
College of Medical Technology, Kyoto University, Kyoto 606-8507, Japan. mmas@kuhp.kyoto-u.ac.jp
Tsunekawa
S
S
Awane
M
M
Fukuda
Y
Y
Murayama
H
H
Igarashi
M
M
Nagata
A
A
Kasai
Y
Y
Totani
M
M
D000208:Acute Disease; D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001119:Arginase / Q000032:analysis* / Q000378:metabolism; D015153:Blotting, Western; D002138:Calibration; D006528:Carcinoma, Hepatocellular / Q000097:blood / Q000175:diagnosis / Q000201:enzymology; D018281:Cholangiocarcinoma / Q000097:blood / Q000175:diagnosis / Q000201:enzymology; D003110:Colonic Neoplasms / Q000097:blood / Q000201:enzymology; D003289:Convalescence; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D004912:Erythrocytes / Q000201:enzymology; D005260:Female; D006505:Hepatitis / Q000097:blood / Q000175:diagnosis / Q000201:enzymology; D006801:Humans; D008099:Liver / Q000201:enzymology*; D008107:Liver Diseases / Q000097:blood / Q000175:diagnosis* / Q000201:enzymology*; D008113:Liver Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000201:enzymology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000911:Antibodies, Monoclonal; D001119:Arginase