Multi-enzyme reference material from established human cell lines and human sources

Abstract A multi-enzyme reference material was prepared from seven enzymes of asparatate aminotransferase (AST, EC 2.6.1.1), alanine aminotransferase (ALT, EC 2.6.1.2), alkaline phosphatase (ALP, EC 3.1.3.1), lactate dehydrogenase (LD, EC 1.1.1.27), creatine kinase (CK, EC 2.7.2.2), γ-glutamyltranspeptidase (γ-GT, EC 2.3.2.2) and amylase (AMY, EC 3.2.1.1) which were purified from human sources including established human cell lines. The enzymatic properties of the material closely resembled those of human serum. In lyophilized form the preparation was stable for at least 200 days when stored at 40°C. Intermethod comparisons of the enzyme activities in 80 clinical specimens were done by correcting the mean values with calibration constants for different assay methods resulting from use of a human serum, the multi-enzyme reference and a commercial control serum. The results from the comparison for the six enzymes of AST, ALT, LD, CK, γ-GT and AMY in use of the multi-enzyme reference were almost the same as those with use of a human serum as a calibrator, but were not satisfactory for ALP. Even though further search for more reliable material for ALP is required the multi-enzyme reference material can be used for standardization in clinical chemistry.