Evaluation of a Commercial Immunoenzymometric Assay Kit for Creatine Kinase MB Isoenzyme Determination Using Monoclonal Antibodies

Abstract

A simultaneous two-site immunoenzymometric assay for creatine kinase MB determination (Hybritech Tandem-Ε CK-MB) using monoclonal antibodies was evaluated and compared with cellulose acetate electrophoresis using fluorometric scanning densitometry.The assay has satisfactory precision (between-day analysis gives a coefficient of Variation between 2.1 and 9.4%) and is not susceptible to interference by concentrations of creatine kinase MM up to 5000 μg/l (3400 U/l) and creatine kinase BB up to 1000 μg/l (1085 U/l). The upper limit of MB isoenzyme concentration in 250 apparently healthy people was 5.5 μg/l. Comparison between the immunoenzymometric assay (y) and electrophoresis (x) yielded the following linear regression equation: y = 0.37 χ -h 1.9, with a correlation coefficient of 0.828. The characteristics of the temporal kinetics of MB isoenzyme, calculated by two methods, in 49 patients with acute myocardial infarction, were nearly identical in terms of the rate of creatine kinase MB release and the time at which the peak value is obtained, but not in terms of the rate of elimination of the isoenzyme. The fractional disappearance rate of MB isoenzyme from the circulation was significantly higher if calculated with Tandem-Ε results rather than with electrophoresis results (-0.035 vs -0.028, p < 0.001). Whereas in the first day after infarction immunoenzymometric assay and electrophoresis had the same clinical sensitivity for identifying patients with acute myocardial infarction, in specimens collected more than 24 hours after the onset of the ehest pain, the clinical sensitivity of the immunoenzymometric method was lower. Our results show that it is stiU premature to draw definitive clinical conclusions from the iinmunoassay results. Evaluierung eines k uflichen immunenzymometrischen Testbestecks zur Bestimmung von Kreatinkinase MBIsoenzym mit monoklonalen Antik rpernZusammenfassung: Ein gleichzeitig auf zwei Teilkomponenten gerichteter enzymimmunometrischer Assay zur Bestimmung von Kreatinkinase MB mit monoklonalen Antik rpern (Hybritech Tandem-Ε CK-MB) wurde ev luiert und mit der CeUuloseacetat-Elektrophorese mit fluorimetrischer Scanning-Densitometrie verglichen. Die Bestimmung hat eine gen gende Pr zision (VK von Tag zu Tag 2,1 -9,4%) und wird durch Konzentrationen von Kreatinkinase MM bis zu 5000 μ$/1 (3400 U/l) und von Kreatinkinase BB bis zu 1000 μg/l (1085 U/l) nicht gest rt. Die obere Grenze der Konzentration von Kreatinkinase MB bei 250 offenbar Gesunden war 5,5 μ §/1. Der Vergleich zwischen enzymometrischem Assay (y) und Elektrophorese (x) ergab die folgende Regressionsgleichung: y == 0,37 x + 1,9 mit einem Korrelationskoeffizienten von 0,828. Die Characteristika des zeitlichen Verlaufs der Konzentration von Isoenzym MB wurden bei 49 Patienten mit akutem Herzinfarkt nach zwei Methoden ermittelt. Sie waren bez glich der Freisetzungsrate von Kreatinkinase MB und der Zeit, zu der der Spitzenwert erhalten wird, nahezu identisch, nicht jedoch bez glich der Eliminationsrate des Isoenzyms. Die relative Schwu...

Short Communication

“…The time-activity curve is similar to that seen in animal models of reperfusion (27) and implies that the rate of MB isoenzyme activity appearance in plasma depends on blood flow to the necrotic zone (28). In this study, peak values of creatine kinase MB activity and mass concentrations in myocardial infarction patients treated conservatively were similar to those reported in our previous paper (19). Moreover, our results agree with previous reports that creatine kinase MB activity reaches its peak value early after successful coronary reperfusion (3 -9).…”

“…Moreover, our results agree with previous reports that creatine kinase MB activity reaches its peak value early after successful coronary reperfusion (3 -9). Previously, we have already shown that the disappearance rate of MB isoenzyme from the circulation of myocardial infarction patients treated conservatively was significantly higher if calculated from Tandem-E results rather than from electrophoresis results (19). As can be seen in table 1, the average rate of decline of creatine kinase MB activity after myocardial infarction was substantially lower than the average rate of decline, calculated in the same fashion, from the immunoenzymometric assay results.…”

“…Double-antibody techniques are now available (10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Double-antibody techniques are now available (10)(11)(12)(13)(14)(15)(16)(17)(18)(19).…”

“…This method has also been evaluated in recent publications (13,15,(17)(18)(19). The assay uses two monoclonal antibodies to determine the creatine kinase MB molecule; one monoclonal antibody is directed toward the B subunit and the other toward the M subunit, producing an assay which is specific for crealine kinase MB.…”

“…The recent introduction of the immunoassay "sandwich" methods, employing anti-monomer M and anti-monomer B antibodies for specific detection of creatine kinase MB, offers an alternative measurement of MB isoenzyme, which quantifies MB mass concentration instead of MB catalytic activity concentration (10)(11)(12)(13)(14)(15)(16)(17)(18). However, our published results showed that an exact comparison between MB activity and mass concentration measurements can be difficult (19). In the present study, we compare the use of one of these new immunoassays (Hybritech Tandem-Ε CK-MB) with the electrophorctic method, routinely used in our laboratory, to assess the reperfusion model of early increase in creatine kinase MB isoenzyme after therapeutic thrombolysis.…”