Development and performance of an enzyme immunoassay to detect creatine kinase isoenzyme MB activity using anti-mitochondrial creatine kinase monoclonal antibodies.
OBJECTIVE
The MB fraction of creatine kinase (CK-MB) has long been used as a cardiac marker. It is known that the CK-MB immunoinhibition method lacks selectivity and accuracy, because the appearance of macro CK type 2, corresponding to mitochondrial creatine kinase (MtCK) in some patient serum may render CK-MB activity measured by conventional method abnormally high. Thus, to improve the specificity and accuracy of the CK-MB assay, we developed two types of monoclonal anti-MtCK antibodies against sarcomeric MtCK and ubiquitous MtCK, and present herein the performance of a new method using these antibodies.


METHODS
The performance of our test for detecting CK-MB activity was compared with other methods, and the range of CK-MB activities in normal human serum was investigated.


RESULTS
The two types of monoclonal antibodies developed by us were isoenzyme-specific to sMtCK or uMtCK. The correlation coefficients of our method and conventional method to electrophoresis were 0.973 and 0.873, respectively. The mean CK-MB activity in normal human serum by our method and the conventional method was 2.4 and 11.7 U/L, respectively. Thus, our data indicated that about 80% of CK-MB activity, determined using the conventional method, seems to correspond to the MtCK activity.


CONCLUSIONS
Our method is novel in offering higher accuracy of measuring true CK-MB contents in human serum as compared to the conventional method. The possibility of accurately estimating CK-MB activity by our method which can inhibit MtCKs in healthy person and patient serum is likely to bring a break-through in clinical diagnostics.
Hoshino
Tadashi
T
Department of Laboratory Medicine, Nihon University School of Medicine, Tokyo, Japan.
Sakai
Yasuhiro
Y
Yamashita
Kazuaki
K
Shirahase
Yasushi
Y
Sakaguchi
Kouji
K
Asaeda
Ayumi
A
Kishi
Kouji
K
Schlattner
Uwe
U
Wallimann
Theo
T
Yanai
Mitsuru
M
Kumasaka
Kazunari
K
D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D000918:Antibody Specificity / Q000187:drug effects; D001666:Binding Sites, Antibody; D052276:Creatine Kinase, BB Form / Q000037:antagonists & inhibitors / Q000097:blood; D052279:Creatine Kinase, MB Form / Q000037:antagonists & inhibitors / Q000097:blood*; D052281:Creatine Kinase, Mitochondrial Form / Q000037:antagonists & inhibitors / Q000097:blood / Q000276:immunology*; D004586:Electrophoresis; D006262:Health; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods* / Q000592:standards*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000097:blood; D008567:Membranes, Artificial; D008970:Molecular Weight; D012016:Reference Values
D000911:Antibodies, Monoclonal; D007527:Isoenzymes; D008567:Membranes, Artificial; D052276:Creatine Kinase, BB Form; D052279:Creatine Kinase, MB Form; D052281:Creatine Kinase, Mitochondrial Form