[Development of a method for the immunological measurement of aspartate aminotransferase with monoclonal antibodies].
OBJECTIVE
For laboratory diagnostics in liver diseases, many enzymes have been used for the assessment of hepatocellular function. Among them, two transaminases, alanine and aspartate aminotransferase, have been regarded as the most sensitive indicators of hepatocellular damage. However, the enhanced enzyme activities of the enzymes do not exactly indicate or represent the cause and progression of diseases in the patients with liver disease. To overcome such limitations, immunological methods have been suggested as one of the alternatives for the replacement or supplement of the conventional enzymatic analysis.


METHODS
In the hope of developing a new assay system for measuring the AST concentration rather than its activity, we have developed a new assay using fluorescence labeled anti-AST monoclonal antibodies. Blood was obtained from a normal population of 234 patients and 43 liver disease patients. The linearity, limit of detection, and performance of the new assay system were tested and evaluated. The comparability of assay was examined with an ELISA and biochemical assays.


RESULTS
The linearity fell in the range of 0-1 mg/L of AST (R=0.995), and the analytical detection limit was 12 microg/L of AST. The mean recovery of the control was 102.4 % in a working range. The precision of the intra- and inter-assay in a range of 50-800 microg/L was CVs < 7% and CVs < 6%, respectively. In the normal population, the mean AST concentration was 35.5 microg/L. The mean AST concentration in patients with liver disease was 266.5 microg/L. The new assay system correlated well with an ELISA and biochemical assay for quantification of AST concentration (R=0.92 and 0.88, respectively; N=43).


CONCLUSIONS
We have developed a new immunological assay using generated monoclonal antibodies to human cytosolic AST and used them for the development of a fluorescent assay measuring the enzyme mass. Cytosolic AST mass in sera could be measured reproducibly by the immunological method. In conclusion, this study has provided us with a new type of tool for an accurate measurement of the enzyme amount in circulation.
Choi
Sunga
S
Boditech Central Research Institute, Chuncheon, Korea.
Kim
Dong Joon
DJ
Choi
Eui Yul
EY
D000911:Antibodies, Monoclonal; D024443:Aspartate Aminotransferase, Cytoplasmic / Q000097:blood* / Q000276:immunology; D005455:Fluorescent Antibody Technique / Q000379:methods*; D006801:Humans; D008107:Liver Diseases / Q000175:diagnosis
D000911:Antibodies, Monoclonal; D024443:Aspartate Aminotransferase, Cytoplasmic